Take a look at this post: Rails Is A Ghetto
This is probably one of the longest rants I have ever seen, interesting but be warned NSFW
Tuesday, January 01, 2008
Friday, December 28, 2007
The Best Geek Story Ever Told
Go to DotNetRocks, download show number 300, fast forward to 57:45 and start listening. It is the funniest geek story I have ever heard. You will not regret it
Here is the link to the show: http://www.dotnetrocks.com/default.aspx?showNum=300
BTW the whole podcast is very interesting in terms of computer history, I highly recommend listening to it.
Here is the link to the show: http://www.dotnetrocks.com/default.aspx?showNum=300
BTW the whole podcast is very interesting in terms of computer history, I highly recommend listening to it.
Thursday, December 27, 2007
A year in review, The 21 + 1 best blog posts on SQLBlog
These are the best posts according to me, it might have been the content or it might have been the comments. Either way here are the 21 + 1 posts I enjoyed the most. But wait the year is not over yet. Doesn't matter no one will write anything good till next year anyway (prove me wrong and I WILL update this post).
The first post is really from last year, I mean really, who writes a post on '2006-12-31T13:49:00.000' (yes that is ISO8601)? Since I did not see the post until 2007 I have included it in the list. I tried not to include more than 2 or 3 posts per blogger, I would have included all Hugo's NULL posts otherwise. What is with the 21 + 1 title? The +1 one is my post about using bitwise logic, it is the last link
Below is the list, let me know if I missed anything you really enjoyed and Happy New Year
The Beatles versus the Stones
How Many Data Files Should I Create for a User Database?
[Editorial] Get rid of the bad apples in IT?
NULL - The database's black hole
Performance Impact of Procedure Calls without Owner Qualification -- SQL Server 2000
Performance Impact of Procedure Calls without Owner Qualification
Did You Know? Run a batch multiple times
Want to Control the Procedure Cache?
Is statistics over non-indexed columns updated by index rebuild?
Xp_cmdshell and permissions
The Perils of Hyperthreading for SQL Server
5 Things every DBA should know like the back of their hand...
Filegroups Part I - Dividing Data for Performance
Did You Know? SP2 does NOT limit the amount of plan cache you can have
Sorted views...
2008: Initializing Table Data with Row Constructors
2008: Row Constructor or Table-Valued Parameter
Anti-Patterns and Malpractices, Volume 1: Tumbling Data
10 lessons from 35K tps
What’s wrong with SELECT * ?
Backup compression in SQL Server 2008
This one is mine
Speed Up Performance And Slash Your Table Size By 90% By Using Bitwise Logic
The first post is really from last year, I mean really, who writes a post on '2006-12-31T13:49:00.000' (yes that is ISO8601)? Since I did not see the post until 2007 I have included it in the list. I tried not to include more than 2 or 3 posts per blogger, I would have included all Hugo's NULL posts otherwise. What is with the 21 + 1 title? The +1 one is my post about using bitwise logic, it is the last link
Below is the list, let me know if I missed anything you really enjoyed and Happy New Year
The Beatles versus the Stones
How Many Data Files Should I Create for a User Database?
[Editorial] Get rid of the bad apples in IT?
NULL - The database's black hole
Performance Impact of Procedure Calls without Owner Qualification -- SQL Server 2000
Performance Impact of Procedure Calls without Owner Qualification
Did You Know? Run a batch multiple times
Want to Control the Procedure Cache?
Is statistics over non-indexed columns updated by index rebuild?
Xp_cmdshell and permissions
The Perils of Hyperthreading for SQL Server
5 Things every DBA should know like the back of their hand...
Filegroups Part I - Dividing Data for Performance
Did You Know? SP2 does NOT limit the amount of plan cache you can have
Sorted views...
2008: Initializing Table Data with Row Constructors
2008: Row Constructor or Table-Valued Parameter
Anti-Patterns and Malpractices, Volume 1: Tumbling Data
10 lessons from 35K tps
What’s wrong with SELECT * ?
Backup compression in SQL Server 2008
This one is mine
Speed Up Performance And Slash Your Table Size By 90% By Using Bitwise Logic
Red Gate SQL Data Generator 1.0 Beta Available For Download
Red Gate have released Red Gate SQL Data Generator 1.0 Beta
From the site:
This tool is aimed at generating test data for SQL Server databases. It can either generate data from scratch or import from existing sources of data.(Like SQL tables or CSV files.)
Features:
- Full SQL Server 2000 and 2005 support
- All data types supported except CLR types
- Pre & Post Scripts execution
- Command-line access version
- Import data from CSV or SQL tables
- Customizable generator settings that allow configuring the amount of nulls, unique values, minimum and maximum values, etc..
- Diverse range of inbuilt generators
The product is not yet complete, and we are looking for user feedback about what features and or functionality you would like in the final product.
*The beta version is set to work until 11 Apr 2008. "
This is a free open beta with the application due to expire on 11 April 2008 with a planned final released sometime before then.
What we really want now is for everyone to use the software and provide us with feedback for the final version. Please let us know on the forums what you like and don't like about the software and what we could do to solve all of your data generation problems!
Visit http://www.red-gate.com/MessageBoard/viewtopic.php?t=6140 for the announcement and download URL
Forums: http://www.red-gate.com/MessageBoard/viewforum.php?f=76
From the site:
This tool is aimed at generating test data for SQL Server databases. It can either generate data from scratch or import from existing sources of data.(Like SQL tables or CSV files.)
Features:
- Full SQL Server 2000 and 2005 support
- All data types supported except CLR types
- Pre & Post Scripts execution
- Command-line access version
- Import data from CSV or SQL tables
- Customizable generator settings that allow configuring the amount of nulls, unique values, minimum and maximum values, etc..
- Diverse range of inbuilt generators
The product is not yet complete, and we are looking for user feedback about what features and or functionality you would like in the final product.
*The beta version is set to work until 11 Apr 2008. "
This is a free open beta with the application due to expire on 11 April 2008 with a planned final released sometime before then.
What we really want now is for everyone to use the software and provide us with feedback for the final version. Please let us know on the forums what you like and don't like about the software and what we could do to solve all of your data generation problems!
Visit http://www.red-gate.com/MessageBoard/viewtopic.php?t=6140 for the announcement and download URL
Forums: http://www.red-gate.com/MessageBoard/viewforum.php?f=76
The Sad State Of Programmers Part 3: General Tips
This is the final part of this series. You can find the first two parts here
Part 1 The Phone Interview
Part 2 The face to face interview.
As far as the resume and interview tips go, I only focused on stuff I have encountered. You can find many tips on the internet and I did not want this post to be a copy of those.
Resume tips
Don’t repeat the same line
If you had 4 jobs and you did more or less the same thing then try to have a different description. If you have to read the same sentence 4 times it gets very boring fast. Try to emphasize what you did at one company versus another. Maybe you worked with a lot more data at one company, maybe your stored procedures had a lot more error checking or had complex business logic. If you list the same thing four times then you are not really differentiating yourself from other people to the prospective interviewer.
List variations of the same keyword
Some companies will feed your resume into a keyword matching program. So in addition to having SQL you also need T-SQL, Structured Query Language and Transact SQL. The first time a recruiter told me this I was baffled, “it is all the same” I told her, she then told me that they used programs and if you don’t score high enough they won’t even consider you.
Do not lie on your resume
If you don’t have experience in SQL Server 2005 then do NOT list it on your resume. It is better not to list it then to be asked about it and admitting you don’t know it. One person admitted he put Java on the resume because the recruiter told him so. Did this get him a job? Of course it did not. Once you have one thing that is not true on your resume the interviewer will wonder what else could be a lie.
Do not try to impress the interviewer on paper
If you have Impressive Object Oriented Skills listed on your resume then you can be sure the interviewer will ask all kinds of OOP stuff. If your skills are really not that impressive then it won’t look that good.
Don’t list your certification right below your name
I saw one resume where the person had the certification right below his name; a certification is not a Ph.D it doesn’t take a lot of money and years to get one. I did notice that the more certifications a person has the less the person knew. I don’t know why this is, maybe it is to compensate for lack of skills, and it is puzzling to me. Your certifications should be listed after your education.
Try to keep your resume concise
If you have a resume which spans 8 pages then try to make it into two or three pages if possible. You can accomplish this by using a smaller font, cutting out duplicate sentences and leaving out sentences that don’t really show any skills. A sentence like the following does not add anything to the resume at all: worked with third party development tools. What does that sentence tell someone? You can use an application or development tool, doesn’t everyone? If you are a web developer then do not list FrontPage on your resume, this will make you look like an amateur.
Use nice paper
Buy yourself some high-quality paper. Your resume is a summary of what you have accomplished so far, don’t use regular paper for that, be proud of your accomplishments use good paper! Keep your resume in pristine condition, buy a folder so that your resume doesn’t get wrinkled.
You worked at the same company for the past 15 years
List all the different positions you have held separately. Listing the positions separately will make the job progression within the company much more obvious.
Interviewing tips
Dress for success
I mentioned it before and I will mention it again: show up for the interview dressed in business attire.
Dress conservative
For women this means the following:
No miniskirts
No high heels or platform shoes
No revealing shirts
No excessive jewelry
No 80s hair styles
Don’t pour gallons of Chanel No 5 on yourself, some people are allergic to perfume and might cut the interview short.
Men should be equally conservative
A navy or black suit is your best bet. You should wear a white shirt; my wife who worked in the banking industry told me a story once about a perfect candidate who did not get hired because he wore a blue shirt. I know it sounds ridiculous but you never know who sits at the other end of the table. I do have friends who over the phone find out about the dress code and ask if they can come in without a suit. I wouldn’t do it; if you have a suit wear it.
No neon colored ties, pick a conservative color.
No excessive jewelry; a wedding band and a watch is all you need. Keep you Cartier love bracelet at home until you get hired.
Don’t be a walking perfume factory, this is not a date.
Shave and trim your hair, if you have long hair keep it out of your face, if you have a beard then keep it neat.
Do your research
Here are two true stories. One person asked if we made shampoos because she passed Johnson & Johnson on the way to our building, she assumed we were a subsidiary. Another person did not know we got acquired by News Corp. it is okay if you don’t know what we do and we did not ask you but do NOT ask what a company does, you should have looked that up before the interview. Do ask what direction the company is going to, how they plan to deal with competition etc.
Behave proper
What you consider normal might not be considered normal by other people. Some people have phobias; they don’t want to be touched for example. I asked a person to explain to me what a deadlock was, he told me to grab the phone then he grabbed my hand and told me to pick up the phone. He said I couldn’t pick up the phone because he locked it. Don’t chew gum. Don’t say “What?’ but ask the interviewer to repeat the question.
Ask questions
Don’t just answer question but also ask questions. Ask about the team, development style, growth of the department and anything else you deem important.
Technical skills and how to keep them up to date
Not everyone works with the latest versions of SQL Server or Visual Studio. Maybe you don’t have a MSDN subscription at work to download the latest versions. When asked if you used the latest version of SQL Server do not say “no because we don’t use it currently at my job”. Some companies will see this as a sign that you are doing the same stuff day in and day out. Download the latest CTP or free express versions, use it at home, build stuff on the weekends. This way you can say that even though you have not used it at work you were still exposed to it. You initiated this yourself and this is an indication that you are willing to learn even in your free time.
I always ask the candidate how the skills are kept up to date. A lot of people have a very tough time answering this question; it might be because they don’t keep it up to date unless they are sent to a training class by their current employer. Instead of paying $40 for a video game or the new HD DVD directors cut invest in a book, this $40 investment will pay itself back very fast (of course you need to read the book and not use it as a paper weight). When you are the one at work who people ask questions to then this will get noticed and you might get promoted sooner. If your employer does not reimburse you for books then keep the recites; if you itemize on your tax return you can use them to lower you marginal tax rate.
Get a RSS reader and subscribe to blogs. There is great content from the SQL Server team, from book authors and from trainers. SQLBlog is a great blog to subscribe to and also check out the roller (http://sqlblog.com/roller/roller.aspx) there are some great blogs there. Visit forums (fora) and newsgroups, here is the SQL server programming one
http://groups.google.com/group/microsoft.public.sqlserver.programming
If you are not comfortable answering question then lurk, read what the masters answer and you will remember it when you have the same problem later on. Don’t worry if you get flamed, I myself answered a question a long time ago and some MVP answered to my answer “Hello table scan anyone”. This brings you back to earth very fast and also makes you verify code for next time. It makes you a better programmer because who wants to get flamed or criticized every day? Not me.
If you have a thick skin then start a blog about programming. Post something bad and you will get comments; this also will make you a better programmer since you will be more careful later on. I remember when I started my blog and I had a post about DBCC PINTABLE, Hugo Kornelis posted a comment how that was being deprecated and should not be used. I could have easily deleted the post and the comment but I did not, this reminds me that I have to double check before I post if I don’t want to get some comments telling me that I am a n00b. Here is the link to that post
http://sqlservercode.blogspot.com/2005/09/put-tables-into-memory.html
This concludes this series, hopefully you learned something from it and look past the negativity to get something positive out of it(wow if that is not a self-help sentence then nothing is)
Happy New Year
Part 1 The Phone Interview
Part 2 The face to face interview.
As far as the resume and interview tips go, I only focused on stuff I have encountered. You can find many tips on the internet and I did not want this post to be a copy of those.
Resume tips
Don’t repeat the same line
If you had 4 jobs and you did more or less the same thing then try to have a different description. If you have to read the same sentence 4 times it gets very boring fast. Try to emphasize what you did at one company versus another. Maybe you worked with a lot more data at one company, maybe your stored procedures had a lot more error checking or had complex business logic. If you list the same thing four times then you are not really differentiating yourself from other people to the prospective interviewer.
List variations of the same keyword
Some companies will feed your resume into a keyword matching program. So in addition to having SQL you also need T-SQL, Structured Query Language and Transact SQL. The first time a recruiter told me this I was baffled, “it is all the same” I told her, she then told me that they used programs and if you don’t score high enough they won’t even consider you.
Do not lie on your resume
If you don’t have experience in SQL Server 2005 then do NOT list it on your resume. It is better not to list it then to be asked about it and admitting you don’t know it. One person admitted he put Java on the resume because the recruiter told him so. Did this get him a job? Of course it did not. Once you have one thing that is not true on your resume the interviewer will wonder what else could be a lie.
Do not try to impress the interviewer on paper
If you have Impressive Object Oriented Skills listed on your resume then you can be sure the interviewer will ask all kinds of OOP stuff. If your skills are really not that impressive then it won’t look that good.
Don’t list your certification right below your name
I saw one resume where the person had the certification right below his name; a certification is not a Ph.D it doesn’t take a lot of money and years to get one. I did notice that the more certifications a person has the less the person knew. I don’t know why this is, maybe it is to compensate for lack of skills, and it is puzzling to me. Your certifications should be listed after your education.
Try to keep your resume concise
If you have a resume which spans 8 pages then try to make it into two or three pages if possible. You can accomplish this by using a smaller font, cutting out duplicate sentences and leaving out sentences that don’t really show any skills. A sentence like the following does not add anything to the resume at all: worked with third party development tools. What does that sentence tell someone? You can use an application or development tool, doesn’t everyone? If you are a web developer then do not list FrontPage on your resume, this will make you look like an amateur.
Use nice paper
Buy yourself some high-quality paper. Your resume is a summary of what you have accomplished so far, don’t use regular paper for that, be proud of your accomplishments use good paper! Keep your resume in pristine condition, buy a folder so that your resume doesn’t get wrinkled.
You worked at the same company for the past 15 years
List all the different positions you have held separately. Listing the positions separately will make the job progression within the company much more obvious.
Interviewing tips
Dress for success
I mentioned it before and I will mention it again: show up for the interview dressed in business attire.
Dress conservative
For women this means the following:
No miniskirts
No high heels or platform shoes
No revealing shirts
No excessive jewelry
No 80s hair styles
Don’t pour gallons of Chanel No 5 on yourself, some people are allergic to perfume and might cut the interview short.
Men should be equally conservative
A navy or black suit is your best bet. You should wear a white shirt; my wife who worked in the banking industry told me a story once about a perfect candidate who did not get hired because he wore a blue shirt. I know it sounds ridiculous but you never know who sits at the other end of the table. I do have friends who over the phone find out about the dress code and ask if they can come in without a suit. I wouldn’t do it; if you have a suit wear it.
No neon colored ties, pick a conservative color.
No excessive jewelry; a wedding band and a watch is all you need. Keep you Cartier love bracelet at home until you get hired.
Don’t be a walking perfume factory, this is not a date.
Shave and trim your hair, if you have long hair keep it out of your face, if you have a beard then keep it neat.
Do your research
Here are two true stories. One person asked if we made shampoos because she passed Johnson & Johnson on the way to our building, she assumed we were a subsidiary. Another person did not know we got acquired by News Corp. it is okay if you don’t know what we do and we did not ask you but do NOT ask what a company does, you should have looked that up before the interview. Do ask what direction the company is going to, how they plan to deal with competition etc.
Behave proper
What you consider normal might not be considered normal by other people. Some people have phobias; they don’t want to be touched for example. I asked a person to explain to me what a deadlock was, he told me to grab the phone then he grabbed my hand and told me to pick up the phone. He said I couldn’t pick up the phone because he locked it. Don’t chew gum. Don’t say “What?’ but ask the interviewer to repeat the question.
Ask questions
Don’t just answer question but also ask questions. Ask about the team, development style, growth of the department and anything else you deem important.
Technical skills and how to keep them up to date
Not everyone works with the latest versions of SQL Server or Visual Studio. Maybe you don’t have a MSDN subscription at work to download the latest versions. When asked if you used the latest version of SQL Server do not say “no because we don’t use it currently at my job”. Some companies will see this as a sign that you are doing the same stuff day in and day out. Download the latest CTP or free express versions, use it at home, build stuff on the weekends. This way you can say that even though you have not used it at work you were still exposed to it. You initiated this yourself and this is an indication that you are willing to learn even in your free time.
I always ask the candidate how the skills are kept up to date. A lot of people have a very tough time answering this question; it might be because they don’t keep it up to date unless they are sent to a training class by their current employer. Instead of paying $40 for a video game or the new HD DVD directors cut invest in a book, this $40 investment will pay itself back very fast (of course you need to read the book and not use it as a paper weight). When you are the one at work who people ask questions to then this will get noticed and you might get promoted sooner. If your employer does not reimburse you for books then keep the recites; if you itemize on your tax return you can use them to lower you marginal tax rate.
Get a RSS reader and subscribe to blogs. There is great content from the SQL Server team, from book authors and from trainers. SQLBlog is a great blog to subscribe to and also check out the roller (http://sqlblog.com/roller/roller.aspx) there are some great blogs there. Visit forums (fora) and newsgroups, here is the SQL server programming one
http://groups.google.com/group/microsoft.public.sqlserver.programming
If you are not comfortable answering question then lurk, read what the masters answer and you will remember it when you have the same problem later on. Don’t worry if you get flamed, I myself answered a question a long time ago and some MVP answered to my answer “Hello table scan anyone”. This brings you back to earth very fast and also makes you verify code for next time. It makes you a better programmer because who wants to get flamed or criticized every day? Not me.
If you have a thick skin then start a blog about programming. Post something bad and you will get comments; this also will make you a better programmer since you will be more careful later on. I remember when I started my blog and I had a post about DBCC PINTABLE, Hugo Kornelis posted a comment how that was being deprecated and should not be used. I could have easily deleted the post and the comment but I did not, this reminds me that I have to double check before I post if I don’t want to get some comments telling me that I am a n00b. Here is the link to that post
http://sqlservercode.blogspot.com/2005/09/put-tables-into-memory.html
This concludes this series, hopefully you learned something from it and look past the negativity to get something positive out of it(wow if that is not a self-help sentence then nothing is)
Happy New Year
Wednesday, December 26, 2007
Alien VS Predator picture
This is priceless
Alien VS Predator picture
In case you wonder which one the predator is, here is a hint
one of them preys on children :-)
Alien VS Predator picture
In case you wonder which one the predator is, here is a hint
one of them preys on children :-)
help hisham to set up an online business, aka begging on the web
Posted here at the microsoft.public.sqlserver.programming forum
Hello world.
I had some problems with my business.
My name is Noor Hisham Bin Ahmad.
I,m from Malaysia.
I need some funds to support my blog because I want set up an online
business.
this is my account number.
Bank Simpanan Nasional
0210029816898886
via western union
How pathetic is that, maybe it should be called Begging 2.0
Hello world.
I had some problems with my business.
My name is Noor Hisham Bin Ahmad.
I,m from Malaysia.
I need some funds to support my blog because I want set up an online
business.
this is my account number.
Bank Simpanan Nasional
0210029816898886
via western union
How pathetic is that, maybe it should be called Begging 2.0
Tuesday, December 25, 2007
Screencast: SQL Server 2008 Change data capture
CDC or Change data capture is a new feature in SQL Server 2008, which is an ability to record changes to table data into another table without writing triggers or some other mechanism, Change data capture records the changes like insert, update, and delete to a table in SQL server thus making the details of the changes available in relational format.
Find more information on the Topic
http://www.microsoft.com/sql/2008/prodinfo/download.mspx https://connect.microsoft.com/SQLServer/content/content.aspx?ContentID=5507
Watch the screencast(SWF)
Watch the screencast(WMV)
Find more information on the Topic
http://www.microsoft.com/sql/2008/prodinfo/download.mspx https://connect.microsoft.com/SQLServer/content/content.aspx?ContentID=5507
Watch the screencast(SWF)
Watch the screencast(WMV)
Monday, December 24, 2007
I am stuffed
Sole, Shrimp, White Wine, Herb de Provence, Tomato Paste, Shallots, Onion, Garlic, Parsley, Pepper and Salt make for a great dinner
SharePoint and SQL Server Reporting Services Posts
blah!bLaH!BLOG has a couple of posts about SharePoint and SQL Server Reporting Services
SharePoint and Reporting Services - Introduction
SharePoint and Reporting Services - Installation and Setup.
SharePoint and Reporting Services - Setup your database.
SharePoint and Reporting Services - Authoring a simple report.
SharePoint and Reporting Services - Enabling end users - the report model.
If you are doing any SharePoint and SQL Server Reporting Services development then do yourself a favor and visit the links above
SharePoint and Reporting Services - Introduction
SharePoint and Reporting Services - Installation and Setup.
SharePoint and Reporting Services - Setup your database.
SharePoint and Reporting Services - Authoring a simple report.
SharePoint and Reporting Services - Enabling end users - the report model.
If you are doing any SharePoint and SQL Server Reporting Services development then do yourself a favor and visit the links above
Kids Might Become Overwhelmed Tomorrow
My wife let each of the kids open one present already because they might become overwhelmed tomorrow
This is the biggest nonsense I have ever heard, she just wanted to see their reaction when opening the toys. Oh well
Maybe I should open one of my presents also.
This is the biggest nonsense I have ever heard, she just wanted to see their reaction when opening the toys. Oh well
Maybe I should open one of my presents also.
Wednesday, December 19, 2007
Stop The Press, Internet Explorer 8 Passes ACID 2 Test
Stop the press,
Internet Explorer 8 Passes ACID 2 Test
Britney Spear's sister is pregnant
Aliens seen crossing the border, these are not illegal and have green skin
Elvis spotted in Greenland
Duke Nukem Forever Teaser Released
So only 3 of these are real. Internet Explorer 8 finally passes the ACID 2 test. Of course some bonehead will say that this is because the Opera suit. Yeah right, they fixed all their stuff in one week.
Channel 9 has a video on their site with two people from the IE team.
The IE team has been very hard at work on IE 8 for the past several months and they hit a huge milestone last Friday evening. The IE dev team checked in a bunch of code that included several new features implemented in the core rendering engine that enable IE to pass the ACID 2 test! This is great news for web developers: IE 8 is going to be our most standards compliant browser to date. Passing ACID 2 is really a combined side effect of all the new features that have been developed for IE 8.
Listen to the podcast(MP3)
Listen to the podcast(WMA)
Download the Video
Watch the Video
Internet Explorer 8 Passes ACID 2 Test
Britney Spear's sister is pregnant
Aliens seen crossing the border, these are not illegal and have green skin
Elvis spotted in Greenland
Duke Nukem Forever Teaser Released
So only 3 of these are real. Internet Explorer 8 finally passes the ACID 2 test. Of course some bonehead will say that this is because the Opera suit. Yeah right, they fixed all their stuff in one week.
Channel 9 has a video on their site with two people from the IE team.
The IE team has been very hard at work on IE 8 for the past several months and they hit a huge milestone last Friday evening. The IE dev team checked in a bunch of code that included several new features implemented in the core rendering engine that enable IE to pass the ACID 2 test! This is great news for web developers: IE 8 is going to be our most standards compliant browser to date. Passing ACID 2 is really a combined side effect of all the new features that have been developed for IE 8.
Listen to the podcast(MP3)
Listen to the podcast(WMA)
Download the Video
Watch the Video
Monday, December 17, 2007
Interview With Joe Celko About The Forthcoming Book Thinking In Sets
I noticed that Joe Celko has a new book coming out soon: Joe Celko's Thinking in Sets: Auxiliary, Temporal, and Virtual Tables in SQL
. I decided to send Joe an email to see if he would be willing to answer some questions I had about the book and SQL in general. To my surprise Joe was more than willing to accommodate my request. The question-and-answer session with Joe that follows was conducted via email.
Is the book geared towards a beginner/intermediate level user or do you have to be an advanced user to really utilize the information in this book?
I would say intermediate level. You need to know enough SQL to do some programming in the language and be experienced enough to see that DDL is as important as DML.
What are the most important things a person can do to master SQL?
The most important thing is to make the leap from procedural programming to declarative programming, from sequential files to sets. The only declarative language that most programmers have seen is spreadsheets. They are nothing like SQL!
I assume you wrote this book because people when they first use a database tend to do the same thing they do in Java, C# or other procedural languages; get a bunch of rows and manipulate them one by one. Is this the number one mistake beginners do?
That is right up there in the top five, for sure! But I think that the classic error is in not knowing how to design the schema in the first place. A bad schema -- denormalized, bad data element names, no constraints, no proper keys, no referential integrity -- leads to trying to correct the flaws in DDL in the DML. If you have a good schema, then the queries, inserts, updates, and deletes are usually fairly easy. All of the "hard work" should be hidden in the database and not spread over the application code and DML.
What is so bad about attribute splitting (somehow these three tables come to mind: Squids, Automobiles and Britney Spears)?
NO, no, no! I coined the phrase a "Squids, Automobiles and Britney Spears" table or column to refer to a table or column which has more than one kind of entity or more than one kind of attribute in it. What makes that phrase so fun is that there is a web page which compared photos of a giant squid and Britney Spears after she cut off her hair. If you actually gave such tables or columns a meaningful name, then you would see that it is not a proper table or column. These nightmares would have names like "hat_or_shoe_size_depending_on_column_five" Attribute splitting is when you take an attribute and make it into two or more tables, columns or rows. The table example is the most common one. How often have you seen a table for each location (split on geography) or a table for each month (temporal split)? This mimics a tape file system, so newbies feel comfortable. When you ask them if they would split a Personnel table into MalePersonnel and FemalePersonnel (split on gender), they immediately see the fallacy. Unfortunately, splits need all kinds of code if they want any data integrity. This code usually re-assembles the data elements back to what they should have been in the first place.
In chapter two of your new book you talk about the new advances in hardware. I have noticed that somehow the amount of data I have to store out paces the advance in hardware and the queries don't run any faster. Will Solid-State Disks finally change that?
I have great hopes for solid state devices. Any solid thing that has to physically move is by definition slower than electricity or light. We are looking at nano-tech, better lasers and a ton of new technology almost every month.
I see you have a whole chapter on auxiliary tables, I am a big fan of those tables myself and I use them to create dates on the fly or split comma delimited strings. In your opinion what percentage of developers does not use them and why should you use them?
Not enough. SQL is a language meant to handle data and not to do computations. Auxiliary tables can be shared among sessions and accessed in parallel. Imagine a complicated but deterministic formula. In a procedural computational model, you hang in a loop and re-do the work for each record in a sequential file. Let me give you a real-world example of that. Corky's BBQ does a huge mail-order business at Christmas time. The pick lists need to include the size of the boxes to be used, so part-time help can do their jobs. When I got this problem, they had discovered that using weights was not right way to go. The approach being attempted was to play "3-D Tetris" with the products. Since that kind of thing is a bitch to program, they were getting nowhere. My approach was to look over a few years of shipping history and find out how many different orders they had shipped and what the smallest box use for each of those orders was. There were only about 5000 configurations and the majority were standard gift packages. Do a relational division and a table look-up to handle 99.98% of the cases and print the phrase "Hand pick this order" on the pick list for the exceptions! In the SQL model, you join an auxiliary table which has the parameters and the result value in each row. You can do this simple multi-column equi-join once in parallel. Wait until the multi-core chips make parallelism the only way to design a computer; then auxiliary table are going to really fly.
I noticed you have a big chapter on VIEWs; do you feel that VIEWs are not utilized enough by developers?
They are used either not enough or too much.
Why do you think we should not use bit or Boolean flags in SQL?
In SQL, to be a data type it must allow NULLs. What is the fundamental nature of a BIT? It is one or zero; there is no NULL concept here! This was a problem for SQL Server, when they made their BIT data type into a numeric that could be NULL-able. The change scrambled a lot of data when it was ported from one release to the next. Bits are low-level, hardware dependent concepts. Are you high end or low end hardware? Do you have 4, 8, 16, 32 or 64 bit machine words? You have use proprietary operators. This defeats the idea of machine independence. Finally, bit flags are used to destroy First Normal Form (1NF) and thus destroy data integrity. As an example, recently in as newsgroup someone wanted to use a 4-bit column to store all the possible colors for a product (red, green, blue, yellow) and get them out with a bit mask (his hardware has a nibble!). But how do you add purple? How do you set up a constraint that no item can be mad with both red and green options? In RDBMS, we discover the state of our data with predicates and not by setting flags at the hardware level.
I have your puzzles book and noticed that you have a paragraph on Sudoku and one on Bin Packing in the last chapter of this book. You have procedural solutions and SQL solutions for most of the material in the chapter; is the SQL solution faster?
There is a funny story on the Sudoku problem. Richard Romley is a retired DBA from Smith-Barney and he decided to play with Sudoku for recreation. He used SQL Server on his home machine and coded a solver in one SELECT statement. The procedure takes 81 parameters (the starting grid) and does an 81-way self-join. It produces ALL the valid answers -- bet you did not know that many published puzzles have multiple solutions! The code is straight forward and depends on the optimizer to handle the search condition logic. Even longer problems with tens of answers run in well under one second. The procedural solvers vary, but I have seen some that stop when they get to the first valid grid. If there is only one solution, they are very fast. But is the right answer actually the *set* of valid grids? Since I am an SQL person, I think so. The procedural solvers can get hung up by backtracking to the starting position when there are a few hundred answers and become very slow. I also strongly recommend getting the Japanese or Chinese editions if you read either language. My two translators cleaned up some old code and added new solutions as we went along.
Should having good naming conventions such as 11179-5 be included in database courses?
Drop them in as soon as you start. If you grow up with good conventions, you will start doing it without thinking about it. When I teach RDBMS, I start with scales and measurement theory so that my students know what data is all about -- whether it is in a database or not.
When can we expect your new book to show up in bookstores?
It was supposed to be out in 2008 February, but we lucked up and it will be out in 2008 January. Production was faster than planned. I guess after seven books, and working with the same people, we have it down pretty well!
A bunch of questions not related to the book
Why do you write technical books?
I have no talent for fiction. I cannot get a plot or characters onto paper to save my life and my dialogues are awful chains of "he said-she said" stiff sentences. My grandfather wrote children's poems in Slovak, and I have even less talent for poetry. I have a number of friends who write detective novels, Science Fiction and Fantasy. They don't consider me a real author because I don't do fiction. I think about trying my hand at YA (Young Adult) books -- Danica McKellar (Winnie from the WONDER YEARS television show) just did a math book for girls, so maybe I could do "A Child's Garden of Normal Forms" or a juvenile detective series called "The Hardware Boys", then go on to a television show called "Query Eye for the Database Guy" or something.
Which of your books was the hardest to write and why?
First edition of SQL FOR SMARTIES! It was my first book and I thought that having written a few hundred magazine columns would make it easy. I was dead wrong -- completely different skill set. I was a year late in delivering the manuscript. After that, I had a system in place.
What is coming down the line? Any new books or updates to current ones?
I am trying to do at least one book per year -- more if I am unemployed and need the advances. My current thoughts are a book on the use of Standards in a database, and one on programming tricks with OLAP functions, CTEs, and other new features in the SQL-2003 Standards. My Morgan-Kaufmann books tend to follow a five year cycle, just like the ANSI/ISO Standards. I also get asked by vendors to do product specific books. I might self-publish something completely off-topic. I have a book on domino games based on my postings and I teach Texas-42 on Royal Carri bean Cruises -- it is a domino game only played in Texas. I also have a book on Pai Gow (a gambling game played with Chinese dominoes) which might sell 10 copies. I will also be doing some video classes, but I don't have details yet.
Which of all the SQL books that you wrote is your favorite?
DATA & DATABASES, which never got the sales of the others. It is more philosophical and concerned with the nature of data instead of programming.
What SQL Server books are on your bookshelf?
Anything I can get by Henderson, Machanic, Moreau, Ben Gan and Delaney. The SQL Server experts are pretty well-known and they publish. This is not true for other products, especially the open-source RDBMS products.
Why do you participate in newsgroups and do you think it is a good idea for beginners to ask questions in newsgroups?
To do some shameless self-promotion, of course :) Newsgroups are a good source of SQL problems and some clever answers that I can use in books and when I am consulting. I also have a pedantic streak I did to get out. And if I am available on a newsgroup, people don't fill up my mailbox at home. And, yes, beginners should use newsgroups for help. But not to have someone else do their job or their homework for them. I like to see the mindset of people who are just learning SQL. It is not enough to see that someone is making a mistake; you want to figure out what lead to that particular mistake. Remember Chernobyl? Everyone did just what they were supposed to do, but there were a few critical assumptions that lead to an event cascade.
What are Cowboy Coders and id-iots?
The term "cowboy coder" is an old one. It means someone who starts coding without any design phase, without any overview to the system as a whole, without any research for industry standards or a company data dictionary. They usually love dialect code and tricks that trade immediate performance for maintainability. The heavy dialect code also gives them job security, since they usually only know one product. An "ID-iot" is a newbie who has no RDBMS education and wants to have the comfort of a sequential file system. So he puts an IDENTITY column on every table as the PRIMARY KEY. Never mind that it is proprietary and non-relational; it is the familiar record number from a file system which can use to mimic pointer chains. He does not understand that rows are not records, tables are not files, columns are not fields and references are constraints and not pointers.
I have been working with Sybase IQ for a little bit; what is your opinion on columnar databases?
Sybase IQ is not the only game in town. I consulted with SAND (nee Marcus, nee Nucleus) years ago. It was one of the first such products. Later I ran into WX2 (nee White Cross) and I am looking at Stonebreaker's Verticia now. Their advantages in parallelism and compressing large amounts of data make them the best choice for Data Warehouses. I would also look at Teradata, which uses hashing. That will become more important as the research on minimal perfect hashing functions gets out of the lab and into products.
Where can we expect to see you in 2008? Any conferences, seminars, trade shows or classrooms perhaps?
I will hopefully be doing some more "SQL Saturdays!" on my weekends. I want to do more webcasts, but I am not sure if I am ready for YouTube. My other travel goal for 2008 is to get to Australia or Japan; I have never gone past Hawaii.
Some of Joe Celko's Books:
SQL for Smarties
SQL Programming Style
Trees and Hierarchies in SQL
SQL Puzzles and Answers
Data and Databases
. I decided to send Joe an email to see if he would be willing to answer some questions I had about the book and SQL in general. To my surprise Joe was more than willing to accommodate my request. The question-and-answer session with Joe that follows was conducted via email.Is the book geared towards a beginner/intermediate level user or do you have to be an advanced user to really utilize the information in this book?
I would say intermediate level. You need to know enough SQL to do some programming in the language and be experienced enough to see that DDL is as important as DML.
What are the most important things a person can do to master SQL?
The most important thing is to make the leap from procedural programming to declarative programming, from sequential files to sets. The only declarative language that most programmers have seen is spreadsheets. They are nothing like SQL!
I assume you wrote this book because people when they first use a database tend to do the same thing they do in Java, C# or other procedural languages; get a bunch of rows and manipulate them one by one. Is this the number one mistake beginners do?
That is right up there in the top five, for sure! But I think that the classic error is in not knowing how to design the schema in the first place. A bad schema -- denormalized, bad data element names, no constraints, no proper keys, no referential integrity -- leads to trying to correct the flaws in DDL in the DML. If you have a good schema, then the queries, inserts, updates, and deletes are usually fairly easy. All of the "hard work" should be hidden in the database and not spread over the application code and DML.
What is so bad about attribute splitting (somehow these three tables come to mind: Squids, Automobiles and Britney Spears)?
NO, no, no! I coined the phrase a "Squids, Automobiles and Britney Spears" table or column to refer to a table or column which has more than one kind of entity or more than one kind of attribute in it. What makes that phrase so fun is that there is a web page which compared photos of a giant squid and Britney Spears after she cut off her hair. If you actually gave such tables or columns a meaningful name, then you would see that it is not a proper table or column. These nightmares would have names like "hat_or_shoe_size_depending_on_column_five" Attribute splitting is when you take an attribute and make it into two or more tables, columns or rows. The table example is the most common one. How often have you seen a table for each location (split on geography) or a table for each month (temporal split)? This mimics a tape file system, so newbies feel comfortable. When you ask them if they would split a Personnel table into MalePersonnel and FemalePersonnel (split on gender), they immediately see the fallacy. Unfortunately, splits need all kinds of code if they want any data integrity. This code usually re-assembles the data elements back to what they should have been in the first place.
In chapter two of your new book you talk about the new advances in hardware. I have noticed that somehow the amount of data I have to store out paces the advance in hardware and the queries don't run any faster. Will Solid-State Disks finally change that?
I have great hopes for solid state devices. Any solid thing that has to physically move is by definition slower than electricity or light. We are looking at nano-tech, better lasers and a ton of new technology almost every month.
I see you have a whole chapter on auxiliary tables, I am a big fan of those tables myself and I use them to create dates on the fly or split comma delimited strings. In your opinion what percentage of developers does not use them and why should you use them?
Not enough. SQL is a language meant to handle data and not to do computations. Auxiliary tables can be shared among sessions and accessed in parallel. Imagine a complicated but deterministic formula. In a procedural computational model, you hang in a loop and re-do the work for each record in a sequential file. Let me give you a real-world example of that. Corky's BBQ does a huge mail-order business at Christmas time. The pick lists need to include the size of the boxes to be used, so part-time help can do their jobs. When I got this problem, they had discovered that using weights was not right way to go. The approach being attempted was to play "3-D Tetris" with the products. Since that kind of thing is a bitch to program, they were getting nowhere. My approach was to look over a few years of shipping history and find out how many different orders they had shipped and what the smallest box use for each of those orders was. There were only about 5000 configurations and the majority were standard gift packages. Do a relational division and a table look-up to handle 99.98% of the cases and print the phrase "Hand pick this order" on the pick list for the exceptions! In the SQL model, you join an auxiliary table which has the parameters and the result value in each row. You can do this simple multi-column equi-join once in parallel. Wait until the multi-core chips make parallelism the only way to design a computer; then auxiliary table are going to really fly.
I noticed you have a big chapter on VIEWs; do you feel that VIEWs are not utilized enough by developers?
They are used either not enough or too much.
Why do you think we should not use bit or Boolean flags in SQL?
In SQL, to be a data type it must allow NULLs. What is the fundamental nature of a BIT? It is one or zero; there is no NULL concept here! This was a problem for SQL Server, when they made their BIT data type into a numeric that could be NULL-able. The change scrambled a lot of data when it was ported from one release to the next. Bits are low-level, hardware dependent concepts. Are you high end or low end hardware? Do you have 4, 8, 16, 32 or 64 bit machine words? You have use proprietary operators. This defeats the idea of machine independence. Finally, bit flags are used to destroy First Normal Form (1NF) and thus destroy data integrity. As an example, recently in as newsgroup someone wanted to use a 4-bit column to store all the possible colors for a product (red, green, blue, yellow) and get them out with a bit mask (his hardware has a nibble!). But how do you add purple? How do you set up a constraint that no item can be mad with both red and green options? In RDBMS, we discover the state of our data with predicates and not by setting flags at the hardware level.
I have your puzzles book and noticed that you have a paragraph on Sudoku and one on Bin Packing in the last chapter of this book. You have procedural solutions and SQL solutions for most of the material in the chapter; is the SQL solution faster?
There is a funny story on the Sudoku problem. Richard Romley is a retired DBA from Smith-Barney and he decided to play with Sudoku for recreation. He used SQL Server on his home machine and coded a solver in one SELECT statement. The procedure takes 81 parameters (the starting grid) and does an 81-way self-join. It produces ALL the valid answers -- bet you did not know that many published puzzles have multiple solutions! The code is straight forward and depends on the optimizer to handle the search condition logic. Even longer problems with tens of answers run in well under one second. The procedural solvers vary, but I have seen some that stop when they get to the first valid grid. If there is only one solution, they are very fast. But is the right answer actually the *set* of valid grids? Since I am an SQL person, I think so. The procedural solvers can get hung up by backtracking to the starting position when there are a few hundred answers and become very slow. I also strongly recommend getting the Japanese or Chinese editions if you read either language. My two translators cleaned up some old code and added new solutions as we went along.
Should having good naming conventions such as 11179-5 be included in database courses?
Drop them in as soon as you start. If you grow up with good conventions, you will start doing it without thinking about it. When I teach RDBMS, I start with scales and measurement theory so that my students know what data is all about -- whether it is in a database or not.
When can we expect your new book to show up in bookstores?
It was supposed to be out in 2008 February, but we lucked up and it will be out in 2008 January. Production was faster than planned. I guess after seven books, and working with the same people, we have it down pretty well!
A bunch of questions not related to the book
Why do you write technical books?
I have no talent for fiction. I cannot get a plot or characters onto paper to save my life and my dialogues are awful chains of "he said-she said" stiff sentences. My grandfather wrote children's poems in Slovak, and I have even less talent for poetry. I have a number of friends who write detective novels, Science Fiction and Fantasy. They don't consider me a real author because I don't do fiction. I think about trying my hand at YA (Young Adult) books -- Danica McKellar (Winnie from the WONDER YEARS television show) just did a math book for girls, so maybe I could do "A Child's Garden of Normal Forms" or a juvenile detective series called "The Hardware Boys", then go on to a television show called "Query Eye for the Database Guy" or something.
Which of your books was the hardest to write and why?
First edition of SQL FOR SMARTIES! It was my first book and I thought that having written a few hundred magazine columns would make it easy. I was dead wrong -- completely different skill set. I was a year late in delivering the manuscript. After that, I had a system in place.
What is coming down the line? Any new books or updates to current ones?
I am trying to do at least one book per year -- more if I am unemployed and need the advances. My current thoughts are a book on the use of Standards in a database, and one on programming tricks with OLAP functions, CTEs, and other new features in the SQL-2003 Standards. My Morgan-Kaufmann books tend to follow a five year cycle, just like the ANSI/ISO Standards. I also get asked by vendors to do product specific books. I might self-publish something completely off-topic. I have a book on domino games based on my postings and I teach Texas-42 on Royal Carri bean Cruises -- it is a domino game only played in Texas. I also have a book on Pai Gow (a gambling game played with Chinese dominoes) which might sell 10 copies. I will also be doing some video classes, but I don't have details yet.
Which of all the SQL books that you wrote is your favorite?
DATA & DATABASES, which never got the sales of the others. It is more philosophical and concerned with the nature of data instead of programming.
What SQL Server books are on your bookshelf?
Anything I can get by Henderson, Machanic, Moreau, Ben Gan and Delaney. The SQL Server experts are pretty well-known and they publish. This is not true for other products, especially the open-source RDBMS products.
Why do you participate in newsgroups and do you think it is a good idea for beginners to ask questions in newsgroups?
To do some shameless self-promotion, of course :) Newsgroups are a good source of SQL problems and some clever answers that I can use in books and when I am consulting. I also have a pedantic streak I did to get out. And if I am available on a newsgroup, people don't fill up my mailbox at home. And, yes, beginners should use newsgroups for help. But not to have someone else do their job or their homework for them. I like to see the mindset of people who are just learning SQL. It is not enough to see that someone is making a mistake; you want to figure out what lead to that particular mistake. Remember Chernobyl? Everyone did just what they were supposed to do, but there were a few critical assumptions that lead to an event cascade.
What are Cowboy Coders and id-iots?
The term "cowboy coder" is an old one. It means someone who starts coding without any design phase, without any overview to the system as a whole, without any research for industry standards or a company data dictionary. They usually love dialect code and tricks that trade immediate performance for maintainability. The heavy dialect code also gives them job security, since they usually only know one product. An "ID-iot" is a newbie who has no RDBMS education and wants to have the comfort of a sequential file system. So he puts an IDENTITY column on every table as the PRIMARY KEY. Never mind that it is proprietary and non-relational; it is the familiar record number from a file system which can use to mimic pointer chains. He does not understand that rows are not records, tables are not files, columns are not fields and references are constraints and not pointers.
I have been working with Sybase IQ for a little bit; what is your opinion on columnar databases?
Sybase IQ is not the only game in town. I consulted with SAND (nee Marcus, nee Nucleus) years ago. It was one of the first such products. Later I ran into WX2 (nee White Cross) and I am looking at Stonebreaker's Verticia now. Their advantages in parallelism and compressing large amounts of data make them the best choice for Data Warehouses. I would also look at Teradata, which uses hashing. That will become more important as the research on minimal perfect hashing functions gets out of the lab and into products.
Where can we expect to see you in 2008? Any conferences, seminars, trade shows or classrooms perhaps?
I will hopefully be doing some more "SQL Saturdays!" on my weekends. I want to do more webcasts, but I am not sure if I am ready for YouTube. My other travel goal for 2008 is to get to Australia or Japan; I have never gone past Hawaii.
Some of Joe Celko's Books:
SQL for Smarties
SQL Programming Style
Trees and Hierarchies in SQL
SQL Puzzles and Answers
Data and Databases
Use XACT_STATE() To Check For Doomed Transactions
Let's say you have the following transaction
BEGIN TRANSACTION TranA
BEGIN TRY
DECLARE @cond INT;
SET @cond = 1
END TRY
BEGIN CATCH
PRINT 'a'
END CATCH;
COMMIT TRAN TranA
This first transaction runs without a problem
Now change value of @cond from 1 to 'A' and run this code below.
BEGIN TRANSACTION TranA
BEGIN TRY
DECLARE @cond INT;
SET @cond = 'A';
END TRY
BEGIN CATCH
PRINT 'a'
END CATCH;
COMMIT TRAN TranA
This transaction will blow up with the following message
Server: Msg 3930, Level 16, State 1, Line 15
The current transaction cannot be committed and cannot support operations that write to the log file. Roll back the transaction.
Server: Msg 3998, Level 16, State 1, Line 1
Uncommittable transaction is detected at the end of the batch. The transaction is rolled back.
We can use XACT_STATE() to check if we need to rollback or not without blowing up. I also used the ERROR_MESSAGE() function to print the error
BEGIN TRANSACTION TranA
BEGIN TRY
DECLARE @cond INT;
SET @cond = 'A';
END TRY
BEGIN CATCH
PRINT ERROR_MESSAGE();
END CATCH;
IF XACT_STATE() =0
BEGIN
COMMIT TRAN TranA
END
ELSE
BEGIN
ROLLBACK TRAN TranA
END
After running that we can see that the following message was printed
Conversion failed when converting the varchar value 'A' to data type int.
We trapped the error, rolled back the transaction and the transaction did not blow up
BEGIN TRANSACTION TranA
BEGIN TRY
DECLARE @cond INT;
SET @cond = 1
END TRY
BEGIN CATCH
PRINT 'a'
END CATCH;
COMMIT TRAN TranA
This first transaction runs without a problem
Now change value of @cond from 1 to 'A' and run this code below.
BEGIN TRANSACTION TranA
BEGIN TRY
DECLARE @cond INT;
SET @cond = 'A';
END TRY
BEGIN CATCH
PRINT 'a'
END CATCH;
COMMIT TRAN TranA
This transaction will blow up with the following message
Server: Msg 3930, Level 16, State 1, Line 15
The current transaction cannot be committed and cannot support operations that write to the log file. Roll back the transaction.
Server: Msg 3998, Level 16, State 1, Line 1
Uncommittable transaction is detected at the end of the batch. The transaction is rolled back.
We can use XACT_STATE() to check if we need to rollback or not without blowing up. I also used the ERROR_MESSAGE() function to print the error
BEGIN TRANSACTION TranA
BEGIN TRY
DECLARE @cond INT;
SET @cond = 'A';
END TRY
BEGIN CATCH
PRINT ERROR_MESSAGE();
END CATCH;
IF XACT_STATE() =0
BEGIN
COMMIT TRAN TranA
END
ELSE
BEGIN
ROLLBACK TRAN TranA
END
After running that we can see that the following message was printed
Conversion failed when converting the varchar value 'A' to data type int.
We trapped the error, rolled back the transaction and the transaction did not blow up
Sunday, December 16, 2007
EXISTS or COUNT(*)
Do you use this
IF (SELECT COUNT(*) FROM SomeTable
WHERE SomeColumn = SomeValue ) > 0
Or do you use this
IF EXISTS (SELECT * FROM SomeTable WHERE SomeColumn = SomeValue )
If you answered COUNT(*) then maybe you should take a look these two articles
Andrew Kelly has a nice post on SQLBlog
http://sqlblog.com/blogs/andrew_kelly/archive/2007/12/15/exists-vs-count-the-battle-never-ends.aspx
Matija Lah has a good post on his snaps & snippets blog
http://milambda.blogspot.com/2006/10/exists-or-not-exists-that-is-question.html
IF (SELECT COUNT(*) FROM SomeTable
WHERE SomeColumn = SomeValue ) > 0
Or do you use this
IF EXISTS (SELECT * FROM SomeTable WHERE SomeColumn = SomeValue )
If you answered COUNT(*) then maybe you should take a look these two articles
Andrew Kelly has a nice post on SQLBlog
http://sqlblog.com/blogs/andrew_kelly/archive/2007/12/15/exists-vs-count-the-battle-never-ends.aspx
Matija Lah has a good post on his snaps & snippets blog
http://milambda.blogspot.com/2006/10/exists-or-not-exists-that-is-question.html
GNET: Even Google Screws Up By Showing A Bunch Of MySQL Messages
When I visited http://www.gnet.com/ today I got greeted by the following error messages. These messages should never be seen by users. What about a friendly message instead? Anyway the mess is below.
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /home/gnet/public_html.v2/libs/adodb/drivers/adodb-mysql.inc.php on line 359
Friday, December 14, 2007
Would You Put Your Database In The Cloud?
Amazon launched a database in the cloud.
Amazon SimpleDB is a web service for running queries on structured data in real time. This service works in close conjunction with Amazon Simple Storage Service (Amazon S3) and Amazon Elastic Compute Cloud (Amazon EC2), collectively providing the ability to store, process and query data sets in the cloud. These services are designed to make web-scale computing easier and more cost-effective for developers.
Traditionally, this type of functionality has been accomplished with a clustered relational database that requires a sizable upfront investment, brings more complexity than is typically needed, and often requires a DBA to maintain and administer. In contrast, Amazon SimpleDB is easy to use and provides the core functionality of a database - real-time lookup and simple querying of structured data - without the operational complexity. Amazon SimpleDB requires no schema, automatically indexes your data and provides a simple API for storage and access. This eliminates the administrative burden of data modeling, index maintenance, and performance tuning. Developers gain access to this functionality within Amazon's proven computing environment, are able to scale instantly, and pay only for what they use.
Amazon Simple Storage Service is a pretty nice service they provide. But would you move your database to Amazon?
You can read more about Amazon SimpleDB here: http://www.amazon.com/b/ref=sc_fe_c_1_3435361_1?ie=UTF8&node=342335011&no=3435361&me=A36L942TSJ2AJA
They also have a developer guide, getting started guide, FAQs and pricing.
What do you think?
Thursday, December 13, 2007
SQL Server Business Intelligence Screencasts
Channel 9 has posted a lot of Business Intelligence screencasts. In case you are bored below is the list. Strangely enough they skip numbers
Business Intelligence #01a: Introduction to Microsoft BI
This screencast provides an overview of Business Intelligence including basic database design concepts, ETL, reporting and analytics.
Business Intelligence #01b: Introduction to SQL Server 2005 Tools and Sample Databases
This screencast introduces the tools within the Microsoft Business Intelligence platform as well as a look at the Adventure Works OLTP and OLAP databases.
Business Intelligence #03a: Loading and Integrating Data from Multiple Sources
This screencast introduces the concept of Data Flow within SQL Server Integration Services (SSIS) including the use of Merge Join and Derived columns.
Business Intelligence #04a: Identifying and Importing New Customers by Using Fuzzy Lookup
This screencast introduces the concept of fuzzy lookup and highlights SQL Server Integration Services (SSIS) support within a Data Flow for performing these tasks.
Business Intelligence #04b: Implementing Slowly Changing Dimensions in the Data Flow
This screencast covers one of the most common scenarios when building a data warehouse. It introduces the concept of Slowly Changing Dimensions (SCD) and how to solve that challenge with SQL Server Integration Services (SSIS).
Business Intelligence #04c: Advanced Package Design
This screencast quickly covers some of the more advanced concepts such as Event Handlers, Logging and Package Configurations using SQL Server Integration Services (SSIS).
Business Intelligence #05a: Designing a Basic Report
This screencast covers the basics of using SQL Server Reporting Services (SSRS) including configuration of data sources and building basic reports. A few small tip, tricks and best practices are also covered.
Business Intelligence #05b: Adding Interactivity to a Report
This screencast shows the viewer how to add parameters and drill through to reports developed using SQL Server Reporting Services (SSRS).
Business Intelligence #06a: Developing a Report Model and Designing a Report Builder Report
This screencast cover building a Report Model in Business Intelligence Development Studio and show how to connect a report using SQL Server Reporting Services (SSRS).
Business Intelligence #07a: Deploying and Accessing Reports
This screencast shows how to embed and deploy SQL Server Reporting Services (SSRS) reports into your applications.
Business Intelligence #09a: Designing Dimensions
This screencast covers building dimensions on a cube built using SQL Server Analysis Services (SSAS).
Business Intelligence #09b: Advanced Dimension Design
This screencast covers optimization of the dimensions built in the previous screencast using SQL Server Analysis Services (SSAS).
Business Intelligence #09c: Using the Cube Wizard
This screencast covers the use of the Cube Wizard including some tips and tricks in SQL Server Analysis Services (SSAS).
Business Intelligence #09d: Introducing Cube Calculations
His screencast adds to the three previous screencasts by adding calculations to an SQL Server Analysis Services (SSAS) cube.
Business Intelligence #10a: Designing Reports on the UDM
This screencast covers optimization of the dimensions built in the previous screencast using SQL Server Analysis Services (SSAS).
Business Intelligence #10b: Exploring Analysis Features of Microsoft Excel 2007
This screencast covers the use of Excel as a tool for viewing data within a cube built with SQL Server Analysis Services (SSAS).
Business Intelligence #11a: More Analysis with Microsoft Excel 2007
This screencast covers using Excel as a powerful tool drill deeper into your information.
Business Intelligence #12a: Introducing Data Mining
This screencast covers general Data Mining techniques using SQL Server Analysis Services (SSAS).
Business Intelligence #12b: Introducing the Table Analysis Tool for Excel 2007
This screencast cover the use of Data Mining Add-Ins for Office using SQL Server Analysis Services (SSAS) as the data mining engine on table data within Excel.
Business Intelligence #14a: Building a PerformancePoint Scorecard
This screencast covers building and publishing scorecards with PerformancePoint.
Business Intelligence #01a: Introduction to Microsoft BI
This screencast provides an overview of Business Intelligence including basic database design concepts, ETL, reporting and analytics.
Business Intelligence #01b: Introduction to SQL Server 2005 Tools and Sample Databases
This screencast introduces the tools within the Microsoft Business Intelligence platform as well as a look at the Adventure Works OLTP and OLAP databases.
Business Intelligence #03a: Loading and Integrating Data from Multiple Sources
This screencast introduces the concept of Data Flow within SQL Server Integration Services (SSIS) including the use of Merge Join and Derived columns.
Business Intelligence #04a: Identifying and Importing New Customers by Using Fuzzy Lookup
This screencast introduces the concept of fuzzy lookup and highlights SQL Server Integration Services (SSIS) support within a Data Flow for performing these tasks.
Business Intelligence #04b: Implementing Slowly Changing Dimensions in the Data Flow
This screencast covers one of the most common scenarios when building a data warehouse. It introduces the concept of Slowly Changing Dimensions (SCD) and how to solve that challenge with SQL Server Integration Services (SSIS).
Business Intelligence #04c: Advanced Package Design
This screencast quickly covers some of the more advanced concepts such as Event Handlers, Logging and Package Configurations using SQL Server Integration Services (SSIS).
Business Intelligence #05a: Designing a Basic Report
This screencast covers the basics of using SQL Server Reporting Services (SSRS) including configuration of data sources and building basic reports. A few small tip, tricks and best practices are also covered.
Business Intelligence #05b: Adding Interactivity to a Report
This screencast shows the viewer how to add parameters and drill through to reports developed using SQL Server Reporting Services (SSRS).
Business Intelligence #06a: Developing a Report Model and Designing a Report Builder Report
This screencast cover building a Report Model in Business Intelligence Development Studio and show how to connect a report using SQL Server Reporting Services (SSRS).
Business Intelligence #07a: Deploying and Accessing Reports
This screencast shows how to embed and deploy SQL Server Reporting Services (SSRS) reports into your applications.
Business Intelligence #09a: Designing Dimensions
This screencast covers building dimensions on a cube built using SQL Server Analysis Services (SSAS).
Business Intelligence #09b: Advanced Dimension Design
This screencast covers optimization of the dimensions built in the previous screencast using SQL Server Analysis Services (SSAS).
Business Intelligence #09c: Using the Cube Wizard
This screencast covers the use of the Cube Wizard including some tips and tricks in SQL Server Analysis Services (SSAS).
Business Intelligence #09d: Introducing Cube Calculations
His screencast adds to the three previous screencasts by adding calculations to an SQL Server Analysis Services (SSAS) cube.
Business Intelligence #10a: Designing Reports on the UDM
This screencast covers optimization of the dimensions built in the previous screencast using SQL Server Analysis Services (SSAS).
Business Intelligence #10b: Exploring Analysis Features of Microsoft Excel 2007
This screencast covers the use of Excel as a tool for viewing data within a cube built with SQL Server Analysis Services (SSAS).
Business Intelligence #11a: More Analysis with Microsoft Excel 2007
This screencast covers using Excel as a powerful tool drill deeper into your information.
Business Intelligence #12a: Introducing Data Mining
This screencast covers general Data Mining techniques using SQL Server Analysis Services (SSAS).
Business Intelligence #12b: Introducing the Table Analysis Tool for Excel 2007
This screencast cover the use of Data Mining Add-Ins for Office using SQL Server Analysis Services (SSAS) as the data mining engine on table data within Excel.
Business Intelligence #14a: Building a PerformancePoint Scorecard
This screencast covers building and publishing scorecards with PerformancePoint.
The Strange Case OF Nulls And Case
Okay it is not Dr. Jekyll and Mr. Hyde but I had to come up with a title. This was a question someone asked yesterday in the sql programming group
http://groups.google.com/group/microsoft.public.sqlserver.programming/browse_thread/thread/126735827b7ae667#
This person had a case statement like this
SELECT
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
END AS items
FROM #INV_ITEMS
This still returned NULLS. Can you spot the flaw? there is no else statement, if there is a value which is not sugar, salt or pepper then a NULL will be returned. let's take a look.
Create this table
CREATE TABLE #INV_ITEMS (COL1 varchar(23))
INSERT #INV_ITEMS VALUES('SUGAR')
INSERT #INV_ITEMS VALUES('SALT')
INSERT #INV_ITEMS VALUES('PEPPER')
INSERT #INV_ITEMS VALUES('WASABI')
Now run this
SELECT
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
END AS items
FROM #INV_ITEMS
Output
--------
SGR
SAL
PEP
NULL
So we get a NULL, but which row is that? We just add the column to find out
SELECT Col1,
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
END AS items
FROM #INV_ITEMS
Output
--------
SUGAR SGR
SALT SAL
PEPPER PEP
WASABI NULL
Aha, it is the wasabi.
Let's try again by including an ELSE
SELECT Col1,
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
ELSE 'UNK'
END AS items
FROM #INV_ITEMS
Output
--------
SUGAR SGR
SALT SAL
PEPPER PEP
WASABI UNK
There we go, it is correct now.
Now let's make it more interesting by inserting a blank, a space and a NULL
INSERT #INV_ITEMS VALUES('')
INSERT #INV_ITEMS VALUES(' ')
INSERT #INV_ITEMS VALUES(NULL)
We can use a combination of NULLIF and RTRIM to filter out blanks, spaces and NULLS
SELECT Col1,
CASE
WHEN NULLIF(RTRIM(COL1),'') IS NULL THEN 'NullOrBlank'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
ELSE 'UNK'
END AS items
FROM #INV_ITEMS
Output
--------
SUGAR SGR
SALT SAL
PEPPER PEP
WASABI UNK
NullOrBlank
NullOrBlank
NULL NullOrBlank
And there it is
DROP TABLE #INV_ITEMS
http://groups.google.com/group/microsoft.public.sqlserver.programming/browse_thread/thread/126735827b7ae667#
This person had a case statement like this
SELECT
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
END AS items
FROM #INV_ITEMS
This still returned NULLS. Can you spot the flaw? there is no else statement, if there is a value which is not sugar, salt or pepper then a NULL will be returned. let's take a look.
Create this table
CREATE TABLE #INV_ITEMS (COL1 varchar(23))
INSERT #INV_ITEMS VALUES('SUGAR')
INSERT #INV_ITEMS VALUES('SALT')
INSERT #INV_ITEMS VALUES('PEPPER')
INSERT #INV_ITEMS VALUES('WASABI')
Now run this
SELECT
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
END AS items
FROM #INV_ITEMS
Output
--------
SGR
SAL
PEP
NULL
So we get a NULL, but which row is that? We just add the column to find out
SELECT Col1,
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
END AS items
FROM #INV_ITEMS
Output
--------
SUGAR SGR
SALT SAL
PEPPER PEP
WASABI NULL
Aha, it is the wasabi.
Let's try again by including an ELSE
SELECT Col1,
CASE
WHEN COL1 IS NULL THEN 'UNK'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
ELSE 'UNK'
END AS items
FROM #INV_ITEMS
Output
--------
SUGAR SGR
SALT SAL
PEPPER PEP
WASABI UNK
There we go, it is correct now.
Now let's make it more interesting by inserting a blank, a space and a NULL
INSERT #INV_ITEMS VALUES('')
INSERT #INV_ITEMS VALUES(' ')
INSERT #INV_ITEMS VALUES(NULL)
We can use a combination of NULLIF and RTRIM to filter out blanks, spaces and NULLS
SELECT Col1,
CASE
WHEN NULLIF(RTRIM(COL1),'') IS NULL THEN 'NullOrBlank'
WHEN COL1 = 'SUGAR' THEN 'SGR'
WHEN COL1 = 'SALT' THEN 'SAL'
WHEN COL1 = 'PEPPER' THEN 'PEP'
ELSE 'UNK'
END AS items
FROM #INV_ITEMS
Output
--------
SUGAR SGR
SALT SAL
PEPPER PEP
WASABI UNK
NullOrBlank
NullOrBlank
NULL NullOrBlank
And there it is
DROP TABLE #INV_ITEMS
Wednesday, December 12, 2007
Retrace : A SQL Profiler Trace Swiss Army Knife
Have you ever needed to find your most expensive queries and quickly grew weary of writing T-SQL against trace tables to try to ferret them out? Have you ever had to wade through gigabytes of trace data just to find one ill-behaving query? Have you ever struggled to decide what performance metrics really matter when analyzing Profiler traces: duration, reads, writes, etc? Ken Henderson's post is about a new tool Bart and Ken wrote to help you do all this and more.
Check it out here: http://blogs.msdn.com/khen1234/archive/2007/12/12/a-sql-profiler-trace-swiss-army-knife.aspx
Check it out here: http://blogs.msdn.com/khen1234/archive/2007/12/12/a-sql-profiler-trace-swiss-army-knife.aspx
SQL Teaser: LEN vs DATALENGTH
This should trip up some people.....
Without running this code what do you think will LEN and DATALENGTH return?
DECLARE @i int
SELECT @i =' 123456789 '
SELECT @i,LEN(@i),DATALENGTH(@i)
Without running this code what do you think will LEN and DATALENGTH return?
DECLARE @i int
SELECT @i =' 123456789 '
SELECT @i,LEN(@i),DATALENGTH(@i)
Tuesday, December 11, 2007
Office 2007 Service Pack 1 Available For Download
Microsoft has just released their first service pack for Microsoft Office 2007, promising lots of bug fixes, performance enhancements, and improved security. The 2007 Microsoft Office suite Service Pack 1 delivers important customer-requested stability and performance improvements, while incorporating further enhancements to user security. This service pack also includes all of the updates released for the 2007 Office suite prior to December of 2007. You can get a more complete description of SP1, including a list of issues that were fixed, in the Microsoft Knowledge Base article 936982: Description of the 2007 Microsoft Office suite Service Pack 1.Access 2007
For third-party applications that use Data Access Object code to synchronize replicated information in a Microsoft Office Access™ 2007 database, Office Access 2007 no longer returns a run-time error that causes the application to close or time out.
Communicator 2007
Microsoft Office Communicator 2007 now presents more accurate presence information and does so with consistent visual cues.
- The icons used to display presence are modified so that users who are red-green colorblind can determine people’s presence status.
- Office Communicator 2007 no longer causes presence icons to flicker when multiple people appear simultaneously.
- Presence information in Office Communicator 2007 and other Microsoft Office applications is consistent in all scenarios.
- Microsoft Office Outlook® 2007 no longer starts in the background along with Office Communicator 2007.
Excel 2007
Several stability, general usability, and compatibility improvements have been incorporated into Microsoft Office Excel® 2007.
- Office Excel 2007 no longer stops responding in some instances when opening a workbook containing calculations.
- Office Excel 2007 workbooks that are saved in Page Break Preview mode and opened in Microsoft Office Excel 2003 no longer produce an error when switched to Normal view.
- When inputting calculations that should result in numbers 65,534 through 65,536, Office Excel 2007 no longer returns the display error of 100,001.
- Office Excel 2007 now retains custom colors on shapes in Excel 2003 worksheets.
- Office Excel 2007 no longer misplaces or wraps labels in charts when the workbook is reopened.
Groove 2007
For Microsoft Office Groove® 2007, issues surrounding the activation of new and previously retired accounts have been resolved.
- Office Groove 2007 no longer places a 60-day limit on retired accounts that are stored in backup files.
- When the auto-activation feature is turned on and invited users open an invitation file (.grv), they are no longer prompted for an activation key or notified of an unconfigured account.
InfoPath 2007 and InfoPath Forms Server
Microsoft Office InfoPath® 2007 benefits from a more consistent user experience, especially with online forms. - When users input data into an Office InfoPath 2007 form using a Web browser, the saved changes are now retained after closing and reopening the form.
- Font size no longer increases when pasting from one rich text box in Office InfoPath 2007 to another.
Outlook 2007
Microsoft Office Outlook 2007 benefits from a number of fixes and enhancements that make the popular messaging client more stable and easier to use.
- Office Outlook 2007 no longer closes unexpectedly when the junk e-mail rule is set to null.
- Body content in HTML-formatted e-mail messages now appears properly in the preview pane or when the message is opened.
- Items moved from an offline folder file (.ost) to a personal folder file (.pst) now display properly in the preview pane.
- In search folders, Office Outlook 2007 now shows the accurate count for unread items that are hidden.
- When scheduling a resource such as a meeting room in meeting requests, the public free/busy information for the resource is now complete and visible in Office Outlook 2007.
- When users forward plain-text e-mail messages with attachments, the body text is now retained.
- If the Mailbox Cleanup wizard starts while the user is dragging a message into a folder, Office Outlook 2007 no longer closes unexpectedly.
PowerPoint 2007
Fixes in Microsoft Office PowerPoint® 2007 make the presentation application even more reliable, especially when used in conjunction with Microsoft Office Outlook Web Access, Web sites that use forms authentication, or event macros.
- Users who have started an event macro in Office PowerPoint 2007 can now advance slides by right-clicking and then choosing Next or Previous.
- When users try to open a presentation in Office PowerPoint 2007 from a Web site using forms authentication, the presentation will now appear properly.
- Users can now open presentations in Office PowerPoint 2007 from e-mail attachments in Office Outlook Web Access.
- Office PowerPoint 2007 no longer crashes when the user programmatically accesses the parent property of the Hyperlinks Collection Object in the Office PowerPoint 2007 object model.
- Text formatting now behaves similarly to previous versions of PowerPoint, where new text retains the formatting of the deleted text instead of using the formatting of the character to the left.
Project 2007 and Project Server 2007
The 2007 Office system SP1 eliminates instances when either Microsoft Office Project 2007 or the accompanying Microsoft Office Project Server 2007 crashes due to a software error.
- Office Project 2007 no longer crashes when users click to view Windows account or Details in the Resources Information dialog box and then perform any other action.
- Office Project 2007 does not produce an error message when a link from one task accesses a task in a different project stored on Office Project Server 2007. This error only occurred when the linked project was renamed.
- Microsoft Office Project Web Access now makes task IDs available and allows users to enter a work estimate when creating a new task.
SharePoint Server 2007
Microsoft Office SharePoint® Server 2007 has improved manageability and compatibility.
- Office SharePoint Server 2007 now has the ability to be installed on Windows Server 2008 providing compatibility and support.
- ASP.NET AJAX has compatibility and support with Office SharePoint Server 2007 including examples for customer web parts build the AJAX 1.0 Control Toolkit and the AJAX 1.0 Extensions for ASP.NET (KB 941955)
- New manageability with STSADM commands for consolidating or repartitioning your content databases, renaming host named site collections, and the ability to scope the people picker to a specific active directory organizational unit.
- Advanced search results now include results with spaces in file names.
- The View by Modified Date function now works correctly in search results.
- Office SharePoint Server 2007 is now able to crawl case-sensitive Web content on computers not running the Windows® operating system.
- Office SharePoint Server 2007 can now index a public folder on a Microsoft Exchange Server with a backslash in the subject.
Visio 2007
Microsoft Office Visio® 2007 now properly redraws shapes when users apply a dynamic connector that is part of a group of shapes in Office Visio 2007.
Word 2007
By taking care of several small stability and usability details, Microsoft Office Word 2007 is a more useful and reliable tool for everyday document creation tasks.
- With Office Word 2007, users can now open and edit embedded objects that contain other embedded objects.
- When using smart documents in Office Word 2007, the Document Actions task pane no longer disappears when moving the pointer into the Reviewing pane. Additionally, task panes opened earlier no longer appear unexpectedly.
- Office Word 2007 properly creates and updates a table of contents in unprotected sections of documents that also contain sections protected for forms.
- Office Word 2007 no longer prints an extra page when users choose a printer with the duplex option enabled.
Download it here: http://www.microsoft.com/downloads/details.aspx?FamilyId=9EC51594-992C-4165-A997-25DA01F388F5&displaylang=en
Monday, December 10, 2007
The Sad State Of Programmers Part 2 : The In Person Interview
This is part two of a three part series. Part one was about the phone interview, this part is about the in person interview. Part three is about general tips
The point of the in person interview is to see if the person will fit in with the rest of the people in the organization. This is where you get asked such wonderful questions like:
How many gas stations are there in the state of New Jersey?
How would you move Mount Fuji?
These questions are usually asked by managers to see how you handle pressure. There is usually no real answer to these questions, you have to logically come up with an answer and solve this puzzle. For example there are 8 million people in New Jersey, these people have 6 million cars. A gas station gets between 3 and 4 cars per minute; this adds up to 4320 cars per day. You would need about 2000 gas stations to serve all these people. All these numbers could be completely wrong; the point is can you logically figure out the steps to ‘solve’ this problem. It doesn’t matter how brilliant you are, if the people that interview you feel that you are a mismatch personality wise you won’t get hired.
Some observations about the process
Dress in business attire
One person dressed very inappropriate, in fact when picking him up at the security desk we thought he was a delivery person. This is not a way to start the face to face interview. I will get into more detail in part 3 of what to wear and not to wear.
You are your own worst enemy
A person was given source code after the phone interview to study. When asked about the code during the face to face interview she mentioned that she just glanced over the code and did not really look at it. Why would you say something like that if you want to get hired? Now, would you consider hiring this person?
Be proper
Do not grimace like you have a squirrel chewing on your big toe while thinking about an answer. Do not chew on your glasses either while thinking about the answer. When you answer the question wrong, the interviewer gives the correct answer don’t say that is what I meant. If that is what you meant then you should have said so, there are of course exceptions but I am talking about real black and white scenarios.
Bring good code
When you bring source code make sure it is the best code you could possible bring. One person was asked about best practices and error handling; he seemed to know this pretty good. Then he offered to show his code, we noticed that he didn’t have any of these best practices in his code. His proc was called sp_ProcName, error handling was wrong and a bunch of other things. In this case it would have been better if the person did not volunteer to show the code.
And now the questions.
I decided to ask every person these exact questions in the face to face interview; depending on how these were answered I would ask a bunch more questions. There are a couple of questions which you couldn’t answer wrong and I did not count them as toward the total score. Here is a list of some of the questions (Alex don’t get mad), I will comment on these questions and give the answers.
How many bytes can you fit in a row, do you know why
How do you enforce that only values between 1 and 10 are allowed in a column
How to check for a valid date if it is passed in as a string
Can you name the 4 isolation levels in SQL Server 2000
How would you select all rows where the date is 20061127
Name some differences between isnull and coalesce
If you create a local temp table and then call a proc is the temp table available inside the proc
What is a SQL injection
Update trigger to capture changed information
Which naming conventions did you use?
Name some best practices which you implemented
Select 3/2
Decimal(6,5)
Create table with PK symbol 10 characters, price 8 digit precision
Add clustered index to that table
What does set xact_abort on
Select * from table where ID <> 1
Favorite SQL Server book
How do you keep your SQL skills up to date?
How many bytes can you fit in a row, do you know why?
I am looking for one of these answers
8K
8060 bytes
Same as a page
8K + overflow column/text columns
If a person does not know the answer to this question then that is ok.
How do you enforce that only values between 1 and 10 are allowed in a column?
I am looking for check constraint as the answer. A bunch of people didn’t answer anything, some answered trigger and one said you should never check in the DB but in the application itself.
How to check for a valid date if it is passed in as a string?
The answer I am looking for is ISDATE() Some people knew this answer, some people answered “convert to datetime and then check for the error” one person said “parse the string”. A bunch of people didn’t answer anything at all
Can you name the 4 isolation levels in SQL Server 2000?
Another nice to have question, if you don’t know it then is not the end of the world. I will also ask the default transaction level
How would you select all rows where the date is 20061127?
I will draw a table on the board with values like these
2007-12-06 15:36:10.293
2007-12-07 00:00:00.000
2007-12-07 15:36:10.293
2007-12-07 15:36:10.293
2007-12-08 00:00:00.000
I am looking for the 3 rows which start with 2007-12-07
The answer I want is this
WHERE date >= ‘20061127’
AND date < ‘20061128’ I don’t want between because it will grab the 2007-12-08 value also, I don’t want convert because that causes an index scan. Less than half the people get the correct answer. Some stuff to read: Do You Know How Between Works With Dates? http://sqlservercode.blogspot.com/2006/10/do-you-know-how-between-works-with.html
How Are Dates Stored In SQL Server?
http://sqlservercode.blogspot.com/2006/11/how-are-dates-stored-in-sql-server.html
The ultimate guide to the datetime datatypes
http://www.karaszi.com/SQLServer/info_datetime.asp
Name some differences between ISNULL and COALESCE
The main answer I am looking for is that ISNULL can only use 2 values while COALESCE can use a lot more. If the person knows other differences then that is also good. I was surprised at the number of people who never heard of COALESCE. Below is some code which shows the differences
There are three major differences besides being ANSI or not between COALESCE and ISNULL
1) COALESCE correctly promotes its arguments to the highest data type in the expression list, ISNULL does not
2) ISNULL can only work with 2 values while COALESCE can take a lot more
3) The alternate value takes the length of the first vale with ISNULL, with COALESCE this doesn't happen
Let's get started, run the following blocks of code
The result is 7, integer math
SELECT 15 / ISNULL(CONVERT(INT,NULL), 2.00)
The result is 7.5, which is correct
SELECT 15 / COALESCE(CONVERT(INT,NULL), 2.00)
You will see that the result is not the same ISNULL does integer math while COALESCE does not
COALESCE correctly promotes its arguments to the highest data type in the expression list.
ISNULL just looks at the first datatype, which is an integer (15) and makes everything an int
COALESCE looks at 2.00 and 15 and then promotes the integer to decimal
Another example is returning the first non null value, ISNULL can only take 2 values while COALESCE can take a whole lot more
Here we have 4 variables and all except for one are null
DECLARE @Var1 VARCHAR(20)
DECLARE @Var2 VARCHAR(20)
DECLARE @Var3 VARCHAR(20)
DECLARE @Var4 VARCHAR(20)
SELECT @Var4 = 'ABC'
--This will return ABC
SELECT COALESCE(@Var1,@Var2,@Var3,@Var4)
Last example.
ISNULL returns NOT while COALESCE returns Not There.
DECLARE @v VARCHAR(3)
SELECT COALESCE(@v,'Not There')
SELECT ISNULL(@v,'Not There')
The alternate value takes the length of the first value with ISNULL, with COALESCE this doesn't happen
If you create a local temp table and then call a proc is the temp table available inside the proc?
The answer is yes and the code is below
--create proc
CREATE PROC TestProc
AS
SET NOCOUNT ON
SELECT * FROM #temp
GO
--create our temp table
CREATE TABLE #temp (id int)
INSERT #temp VALUES(1)
INSERT #temp VALUES(2)
INSERT #temp VALUES(3)
--exec proc
EXEC TestProc
What is SQL injection?
People either knew or did not know about SQL injection, the ones who knew also knew what to do to prevent it. A little less than half the people interviewed knew what it was.
Some stuff to read:
SQL injection cheat sheet.
http://ferruh.mavituna.com/makale/sql-injection-cheatsheet/
The Curse and Blessings of Dynamic SQL
http://www.sommarskog.se/dynamic_sql.html
Update trigger to capture changed information
In drew two tables on the whiteboard and explained to the people that I wanted to move data into a history table only when the value in a certain column changed. I was looking for several things
If the person knew about inserted and deleted tables
If the person would code the trigger for multi row statements and not assign the value to a variable
If the person knew about IF UPDATE(Column) and that this was true even if the table was updated with the same value
If the person would join inserted and deleted to make sure no row would be inserted if the value didn’t change
Some stuff to read:
Fun With SQL server Update Triggers
http://sqlservercode.blogspot.com/2005/12/fun-with-sql-server-update-triggers.html
What naming conventions did you use?
Here I wanted to hear if the person had any standards, I would also ask for an example of a proc name hoping sp_ProcName wouldn’t be answered
Some stuff to read:
The ISO organization has a document on their site. The one that deals with naming conventions is 11179-5 The link will point to a zip file which has a pdf file in it. The TOC of this pdf file is below Contents Foreword 1 Scope 2 Normative references 3 Terms and definitions 4 Data Identifiers within a registry 5 Identification 6 Names 6.1 Names in a registry 6.2 Naming conventions 7 Development of naming conventions 7.1 Introduction 7.2 Scope principle 7.3 Authority principle 7.4 Semantic principle 7.5 Syntactic principle 7.6 Lexical principle 7.7 Uniqueness principle Annex A (informative) Example naming conventions for names within an MDR registry Annex B (informative) Example naming conventions for Asian languages
What best practices did you implement?
There is a whole range of possible answers here and I won’t get into detail.
Select 3/2
When I wrote Select 3/2 on the board and ask what this would return several people looked at me if I was crazy. The answer is of course 1 because of integer math. I ask this question because we run reports which deal with calculation with integers. Take a look at this code to see what you can do to ‘fix’ the issue
Run this
--Integer math
DECLARE @Val1 INT,@val2 INT
SELECT @Val1 =3, @val2 =2
SELECT @Val1/@Val2
GO
It returns 1
Now run this
DECLARE @Val1 INT,@val2 INT
SELECT @Val1 =3, @val2 =2
--Implicit
SELECT @Val1/(@Val2*1.0)
--Explicit
SELECT CONVERT(DECIMAL(18,4),@Val1)/@Val2
GO
Both of those return 1.50000000000000
So what does @val2*1.0 do? well run this
DECLARE @Val1 INT,@val2 INT
SELECT @Val1 =3, @val2 =2
SELECT CAST(SQL_VARIANT_PROPERTY(@val2*1.0,'BaseType') AS VARCHAR(20)) + '(' +
CAST(SQL_VARIANT_PROPERTY(@val2*1.0,'Precision') AS VARCHAR(10)) + ',' +
CAST(SQL_VARIANT_PROPERTY(@val2*1.0,'Scale') AS VARCHAR(10)) + ')'
As you can see it is numeric(13,1)
Decimal(6,5)
What is the greatest value that Decimal(6,5) can hold? A lot of people answered 999999.99999 which is wrong of course. The total number of numbers is 6 and 5 of those are after the comma. So the answer is 9.99999. Run this to try it out for yourself.
Create table with PK symbol 10 characters, price 8 digit precision
I would tell people to create a table with 2 columns
1 with a column named symbol variable character 10 in length, it would also be a primary key
Price which was decimal and can hold a number as big as 999999.99999999
They had to do this on the whiteboard in T-SQL (create table…..)
Most people got the PK syntax wrong; some people got the decimal wrong. The reason I am asking this question is because we can’t go on a production machine with Enterprise Manager and start clicking. You might not have permissions to make changes, you need to supply a script which other people might run.
Add clustered index to that table
My next question would be to add a clustered index to that table. The correct answer would be you can’t since the table has a primary key which is a clustered index by default
What does set xact_abort on do
Only one person answered this question correctly, this was another nice to know question. I did explain to people why you would use this, sometimes you cannot trap the error and this statement will enable you to rollback everything up until that point.
Some stuff to read:
Implementing Error Handling with Stored Procedures
http://www.sommarskog.se/error-handling-II.html
Error Handling in SQL Server – a Background.
http://www.sommarskog.se/error-handling-I.html
Select * from table where ID <> 1
I would draw a table with three rows, the values being 1, 2 and null. Then I would ask what would be returned after running this query
SELECT * FROM #temp WHERE id <> 1
A lot of people chocked on this one, the answer is 2 of course, null will not be returned. Test it out for yourself
CREATE TABLE #temp (id int)
INSERT #temp VALUES(1)
INSERT #temp VALUES(2)
INSERT #temp VALUES(null)
SELECT * FROM #temp WHERE id <> 1
Some stuff to read:
NULL trouble In SQL Server Land
http://sqlservercode.blogspot.com/2006/01/null-trouble-in-sql-server-land.html
NULL - The database's black hole
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/07/06/null-ndash-the-database-rsquo-s-black-hole.aspx
The logic of three-valued logic
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/07/17/the-logic-of-three-valued-logic.aspx
Dr. Unknown, or how I learned to stop worrying and love the NULL
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/09/22/dr-unknown-or-how-i-learned-to-stop-worrying-and-love-the-null.aspx
What if null if null is null null null is null?
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/09/30/what-if-null-if-null-is-null-null-null-is-null.aspx
Favorite SQL Server book
Here something bizarre happened; there were several people who did not have a SQL Server book at all. I did not understand this; how do you not have a SQL server books as a developer? A bunch of people listed Ken Henderson’s Guru book, some of them listed Inside SQL Server and one person answered SQL Server 2005 unleashed (I have the 2000 version, I should check this one out). In part three I will give you a list of my favorite books.
How do you keep your SQL skills up to date?
I am looking for websites, books, blogs, conferences, webinars, podcasts etc. Some people answered Books On Line. One person answered certification (I will address certification and my dislike of them in part 3). I was surprised by the difficulty that people had in answering this question. SQL Server Central was a popular website as well as DevX and MSDN. Nobody answered podcast at all. I would ask people if they played around with the latest CTP of SQL Server 2008, most of them were not aware that this was available to the general public. I did interview a bunch of SQL Server authors and I asked them what they did or would do to master SQL. You can read those interviews by clicking on the links below
Louis Davidson
Itzik Ben-Gan
Ken Henderson
Adam Machanic
Kalen Delaney
That was it fort part two, I originally wanted to put more content here but I was afraid it would become too long, I moved some of that stuff to part three.
The point of the in person interview is to see if the person will fit in with the rest of the people in the organization. This is where you get asked such wonderful questions like:
How many gas stations are there in the state of New Jersey?
How would you move Mount Fuji?
These questions are usually asked by managers to see how you handle pressure. There is usually no real answer to these questions, you have to logically come up with an answer and solve this puzzle. For example there are 8 million people in New Jersey, these people have 6 million cars. A gas station gets between 3 and 4 cars per minute; this adds up to 4320 cars per day. You would need about 2000 gas stations to serve all these people. All these numbers could be completely wrong; the point is can you logically figure out the steps to ‘solve’ this problem. It doesn’t matter how brilliant you are, if the people that interview you feel that you are a mismatch personality wise you won’t get hired.
Some observations about the process
Dress in business attire
One person dressed very inappropriate, in fact when picking him up at the security desk we thought he was a delivery person. This is not a way to start the face to face interview. I will get into more detail in part 3 of what to wear and not to wear.
You are your own worst enemy
A person was given source code after the phone interview to study. When asked about the code during the face to face interview she mentioned that she just glanced over the code and did not really look at it. Why would you say something like that if you want to get hired? Now, would you consider hiring this person?
Be proper
Do not grimace like you have a squirrel chewing on your big toe while thinking about an answer. Do not chew on your glasses either while thinking about the answer. When you answer the question wrong, the interviewer gives the correct answer don’t say that is what I meant. If that is what you meant then you should have said so, there are of course exceptions but I am talking about real black and white scenarios.
Bring good code
When you bring source code make sure it is the best code you could possible bring. One person was asked about best practices and error handling; he seemed to know this pretty good. Then he offered to show his code, we noticed that he didn’t have any of these best practices in his code. His proc was called sp_ProcName, error handling was wrong and a bunch of other things. In this case it would have been better if the person did not volunteer to show the code.
And now the questions.
I decided to ask every person these exact questions in the face to face interview; depending on how these were answered I would ask a bunch more questions. There are a couple of questions which you couldn’t answer wrong and I did not count them as toward the total score. Here is a list of some of the questions (Alex don’t get mad), I will comment on these questions and give the answers.
How many bytes can you fit in a row, do you know why
How do you enforce that only values between 1 and 10 are allowed in a column
How to check for a valid date if it is passed in as a string
Can you name the 4 isolation levels in SQL Server 2000
How would you select all rows where the date is 20061127
Name some differences between isnull and coalesce
If you create a local temp table and then call a proc is the temp table available inside the proc
What is a SQL injection
Update trigger to capture changed information
Which naming conventions did you use?
Name some best practices which you implemented
Select 3/2
Decimal(6,5)
Create table with PK symbol 10 characters, price 8 digit precision
Add clustered index to that table
What does set xact_abort on
Select * from table where ID <> 1
Favorite SQL Server book
How do you keep your SQL skills up to date?
How many bytes can you fit in a row, do you know why?
I am looking for one of these answers
8K
8060 bytes
Same as a page
8K + overflow column/text columns
If a person does not know the answer to this question then that is ok.
How do you enforce that only values between 1 and 10 are allowed in a column?
I am looking for check constraint as the answer. A bunch of people didn’t answer anything, some answered trigger and one said you should never check in the DB but in the application itself.
How to check for a valid date if it is passed in as a string?
The answer I am looking for is ISDATE() Some people knew this answer, some people answered “convert to datetime and then check for the error” one person said “parse the string”. A bunch of people didn’t answer anything at all
Can you name the 4 isolation levels in SQL Server 2000?
Another nice to have question, if you don’t know it then is not the end of the world. I will also ask the default transaction level
How would you select all rows where the date is 20061127?
I will draw a table on the board with values like these
2007-12-06 15:36:10.293
2007-12-07 00:00:00.000
2007-12-07 15:36:10.293
2007-12-07 15:36:10.293
2007-12-08 00:00:00.000
I am looking for the 3 rows which start with 2007-12-07
The answer I want is this
WHERE date >= ‘20061127’
AND date < ‘20061128’ I don’t want between because it will grab the 2007-12-08 value also, I don’t want convert because that causes an index scan. Less than half the people get the correct answer. Some stuff to read: Do You Know How Between Works With Dates? http://sqlservercode.blogspot.com/2006/10/do-you-know-how-between-works-with.html
How Are Dates Stored In SQL Server?
http://sqlservercode.blogspot.com/2006/11/how-are-dates-stored-in-sql-server.html
The ultimate guide to the datetime datatypes
http://www.karaszi.com/SQLServer/info_datetime.asp
Name some differences between ISNULL and COALESCE
The main answer I am looking for is that ISNULL can only use 2 values while COALESCE can use a lot more. If the person knows other differences then that is also good. I was surprised at the number of people who never heard of COALESCE. Below is some code which shows the differences
There are three major differences besides being ANSI or not between COALESCE and ISNULL
1) COALESCE correctly promotes its arguments to the highest data type in the expression list, ISNULL does not
2) ISNULL can only work with 2 values while COALESCE can take a lot more
3) The alternate value takes the length of the first vale with ISNULL, with COALESCE this doesn't happen
Let's get started, run the following blocks of code
The result is 7, integer math
SELECT 15 / ISNULL(CONVERT(INT,NULL), 2.00)
The result is 7.5, which is correct
SELECT 15 / COALESCE(CONVERT(INT,NULL), 2.00)
You will see that the result is not the same ISNULL does integer math while COALESCE does not
COALESCE correctly promotes its arguments to the highest data type in the expression list.
ISNULL just looks at the first datatype, which is an integer (15) and makes everything an int
COALESCE looks at 2.00 and 15 and then promotes the integer to decimal
Another example is returning the first non null value, ISNULL can only take 2 values while COALESCE can take a whole lot more
Here we have 4 variables and all except for one are null
DECLARE @Var1 VARCHAR(20)
DECLARE @Var2 VARCHAR(20)
DECLARE @Var3 VARCHAR(20)
DECLARE @Var4 VARCHAR(20)
SELECT @Var4 = 'ABC'
--This will return ABC
SELECT COALESCE(@Var1,@Var2,@Var3,@Var4)
Last example.
ISNULL returns NOT while COALESCE returns Not There.
DECLARE @v VARCHAR(3)
SELECT COALESCE(@v,'Not There')
SELECT ISNULL(@v,'Not There')
The alternate value takes the length of the first value with ISNULL, with COALESCE this doesn't happen
If you create a local temp table and then call a proc is the temp table available inside the proc?
The answer is yes and the code is below
--create proc
CREATE PROC TestProc
AS
SET NOCOUNT ON
SELECT * FROM #temp
GO
--create our temp table
CREATE TABLE #temp (id int)
INSERT #temp VALUES(1)
INSERT #temp VALUES(2)
INSERT #temp VALUES(3)
--exec proc
EXEC TestProc
What is SQL injection?
People either knew or did not know about SQL injection, the ones who knew also knew what to do to prevent it. A little less than half the people interviewed knew what it was.
Some stuff to read:
SQL injection cheat sheet.
http://ferruh.mavituna.com/makale/sql-injection-cheatsheet/
The Curse and Blessings of Dynamic SQL
http://www.sommarskog.se/dynamic_sql.html
Update trigger to capture changed information
In drew two tables on the whiteboard and explained to the people that I wanted to move data into a history table only when the value in a certain column changed. I was looking for several things
If the person knew about inserted and deleted tables
If the person would code the trigger for multi row statements and not assign the value to a variable
If the person knew about IF UPDATE(Column) and that this was true even if the table was updated with the same value
If the person would join inserted and deleted to make sure no row would be inserted if the value didn’t change
Some stuff to read:
Fun With SQL server Update Triggers
http://sqlservercode.blogspot.com/2005/12/fun-with-sql-server-update-triggers.html
What naming conventions did you use?
Here I wanted to hear if the person had any standards, I would also ask for an example of a proc name hoping sp_ProcName wouldn’t be answered
Some stuff to read:
The ISO organization has a document on their site. The one that deals with naming conventions is 11179-5 The link will point to a zip file which has a pdf file in it. The TOC of this pdf file is below Contents Foreword 1 Scope 2 Normative references 3 Terms and definitions 4 Data Identifiers within a registry 5 Identification 6 Names 6.1 Names in a registry 6.2 Naming conventions 7 Development of naming conventions 7.1 Introduction 7.2 Scope principle 7.3 Authority principle 7.4 Semantic principle 7.5 Syntactic principle 7.6 Lexical principle 7.7 Uniqueness principle Annex A (informative) Example naming conventions for names within an MDR registry Annex B (informative) Example naming conventions for Asian languages
What best practices did you implement?
There is a whole range of possible answers here and I won’t get into detail.
Select 3/2
When I wrote Select 3/2 on the board and ask what this would return several people looked at me if I was crazy. The answer is of course 1 because of integer math. I ask this question because we run reports which deal with calculation with integers. Take a look at this code to see what you can do to ‘fix’ the issue
Run this
--Integer math
DECLARE @Val1 INT,@val2 INT
SELECT @Val1 =3, @val2 =2
SELECT @Val1/@Val2
GO
It returns 1
Now run this
DECLARE @Val1 INT,@val2 INT
SELECT @Val1 =3, @val2 =2
--Implicit
SELECT @Val1/(@Val2*1.0)
--Explicit
SELECT CONVERT(DECIMAL(18,4),@Val1)/@Val2
GO
Both of those return 1.50000000000000
So what does @val2*1.0 do? well run this
DECLARE @Val1 INT,@val2 INT
SELECT @Val1 =3, @val2 =2
SELECT CAST(SQL_VARIANT_PROPERTY(@val2*1.0,'BaseType') AS VARCHAR(20)) + '(' +
CAST(SQL_VARIANT_PROPERTY(@val2*1.0,'Precision') AS VARCHAR(10)) + ',' +
CAST(SQL_VARIANT_PROPERTY(@val2*1.0,'Scale') AS VARCHAR(10)) + ')'
As you can see it is numeric(13,1)
Decimal(6,5)
What is the greatest value that Decimal(6,5) can hold? A lot of people answered 999999.99999 which is wrong of course. The total number of numbers is 6 and 5 of those are after the comma. So the answer is 9.99999. Run this to try it out for yourself.
Create table with PK symbol 10 characters, price 8 digit precision
I would tell people to create a table with 2 columns
1 with a column named symbol variable character 10 in length, it would also be a primary key
Price which was decimal and can hold a number as big as 999999.99999999
They had to do this on the whiteboard in T-SQL (create table…..)
Most people got the PK syntax wrong; some people got the decimal wrong. The reason I am asking this question is because we can’t go on a production machine with Enterprise Manager and start clicking. You might not have permissions to make changes, you need to supply a script which other people might run.
Add clustered index to that table
My next question would be to add a clustered index to that table. The correct answer would be you can’t since the table has a primary key which is a clustered index by default
What does set xact_abort on do
Only one person answered this question correctly, this was another nice to know question. I did explain to people why you would use this, sometimes you cannot trap the error and this statement will enable you to rollback everything up until that point.
Some stuff to read:
Implementing Error Handling with Stored Procedures
http://www.sommarskog.se/error-handling-II.html
Error Handling in SQL Server – a Background.
http://www.sommarskog.se/error-handling-I.html
Select * from table where ID <> 1
I would draw a table with three rows, the values being 1, 2 and null. Then I would ask what would be returned after running this query
SELECT * FROM #temp WHERE id <> 1
A lot of people chocked on this one, the answer is 2 of course, null will not be returned. Test it out for yourself
CREATE TABLE #temp (id int)
INSERT #temp VALUES(1)
INSERT #temp VALUES(2)
INSERT #temp VALUES(null)
SELECT * FROM #temp WHERE id <> 1
Some stuff to read:
NULL trouble In SQL Server Land
http://sqlservercode.blogspot.com/2006/01/null-trouble-in-sql-server-land.html
NULL - The database's black hole
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/07/06/null-ndash-the-database-rsquo-s-black-hole.aspx
The logic of three-valued logic
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/07/17/the-logic-of-three-valued-logic.aspx
Dr. Unknown, or how I learned to stop worrying and love the NULL
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/09/22/dr-unknown-or-how-i-learned-to-stop-worrying-and-love-the-null.aspx
What if null if null is null null null is null?
http://sqlblog.com/blogs/hugo_kornelis/archive/2007/09/30/what-if-null-if-null-is-null-null-null-is-null.aspx
Favorite SQL Server book
Here something bizarre happened; there were several people who did not have a SQL Server book at all. I did not understand this; how do you not have a SQL server books as a developer? A bunch of people listed Ken Henderson’s Guru book, some of them listed Inside SQL Server and one person answered SQL Server 2005 unleashed (I have the 2000 version, I should check this one out). In part three I will give you a list of my favorite books.
How do you keep your SQL skills up to date?
I am looking for websites, books, blogs, conferences, webinars, podcasts etc. Some people answered Books On Line. One person answered certification (I will address certification and my dislike of them in part 3). I was surprised by the difficulty that people had in answering this question. SQL Server Central was a popular website as well as DevX and MSDN. Nobody answered podcast at all. I would ask people if they played around with the latest CTP of SQL Server 2008, most of them were not aware that this was available to the general public. I did interview a bunch of SQL Server authors and I asked them what they did or would do to master SQL. You can read those interviews by clicking on the links below
Louis Davidson
Itzik Ben-Gan
Ken Henderson
Adam Machanic
Kalen Delaney
That was it fort part two, I originally wanted to put more content here but I was afraid it would become too long, I moved some of that stuff to part three.
Saturday, December 08, 2007
Video: Microsoft SQL Server 2008 Nov CTP - Spatial (Part 1/3)
Head over to Channel 9 and watch the first part of a three part series about the spatial data type in SQL server 2008. Besides video formats there are also mp3 and wma versions in case you just want to listen to it
Watch it here: http://channel9.msdn.com/ShowPost.aspx?PostID=363495#363495
Watch it here: http://channel9.msdn.com/ShowPost.aspx?PostID=363495#363495
Wednesday, December 05, 2007
The Most Natural Set Option
SET ANSI_NULL_DFLT_OFF ON
this is what this means, in English....
Set the setting ANSI NULL Default Off to ON
Why not just SET ANSI_NULL_DFLT [ON|OFF]?
This is even worse than SET NOCOUNT ON
this is what this means, in English....
Set the setting ANSI NULL Default Off to ON
Why not just SET ANSI_NULL_DFLT [ON|OFF]?
This is even worse than SET NOCOUNT ON
Sunday, December 02, 2007
The Sad State Of Programmers Part 1 : The Phone Interview.
This is going to be a three part series.
Part 1 The phone interview.
Part 2 The face to face interview.
Part 3 Some tips and observations
A while back I posted that we are looking for a SQL/.NET/FoxPro developer. I did this because we had a real hard time finding this person. I am happy to inform you that we did find this person and he will start in two weeks. Interestingly enough we hired the person with the least years of experience (on paper). This person knew more that people with three times his experience in years.
These days when looking for a programmer you have to do phone interviews if you don’t want to waste an incredible amount of time. A phone interview enables you to assess the skill set of a potential employee without wasting time by picking him up, getting a security badge, booking a conference room etc. A phone interview is also good for the candidate since he/she doesn’t have to travel or dress up to do the interview.
Some things are difficult to ask over the phone but if the candidate looks (or should that be sounds) good then you can ask those questions when you bring the person in. Some people will prepare for a phone interview by having all their books and notes in front of them. They will ask you to repeat the question and while you do so you can hear them flipping pages frantically. So you might be able to cheat on the phone interview but be assured that if you do not know your stuff that you will fall flat on your face on a face to face interview (no pun intended).
One thing I never understood is the fact that it takes a person one minute to answer a question. You either know or don’t know the question. Keep your answers concise, do not spend 3 minutes explaining to me what the difference is between a clustered and non clustered index.
I had to reword my questions slightly because when I asked a question like “Do you know what the difference is between a clustered index and a non clustered index?” some people would reply “yes”. Because of that I changed the question to “Describe what the difference is between a clustered index and a non clustered index?”
Do not shoot yourself in the foot by giving me additional information which is wrong. I asked for the fastest way to empty a table. Almost every single person who knew about truncate added that you cannot rollback a truncate statement. I wrote about that myth a couple of months ago: SQL Myth: Truncate Cannot Be Rolled Back Because It Is Not Logged
I tend to ask between 20 and 40 questions, if I see the candidate’s skill is not good enough I don’t ask everything. Some of the questions are esoteric but I simply ask these questions to get a feel of the overall skill level; it doesn’t matter if they answer these wrong. You can find a list of question here: How Well Do You Interview And Do You Use Wizard Driven Programming?
Here are some interesting answers from the interviews.
Almost every single person answered that an index scan is better than an index seek.
There were several people with SQL Server 2005 experience, these people couldn’t name one single new thing introduced in SQL Server 2005. I asked about windowing functions, DMVs, pivot, apply and more, this was all Greek to them. One person had on her resume that she developed an app in SQL Server 2005. When I asked about her experience she told me she just started to read about SQL Server 2005. This is a big show stopper, sometimes headhunters/recruiters will tell you to just add it to your resume, I wouldn’t do it because it makes you look bad. If the SQL Server 2005 experience is not true what else could be made up? One person had on his resume that he optimized complex stored procedures, when I asked how he did it, he replied that he only selected the rows he needed instead of the whole table. This obviously didn’t answer my question.
That is it for the phone interview, part 2 will be up in a day or two.
Part 1 The phone interview.
Part 2 The face to face interview.
Part 3 Some tips and observations
A while back I posted that we are looking for a SQL/.NET/FoxPro developer. I did this because we had a real hard time finding this person. I am happy to inform you that we did find this person and he will start in two weeks. Interestingly enough we hired the person with the least years of experience (on paper). This person knew more that people with three times his experience in years.
These days when looking for a programmer you have to do phone interviews if you don’t want to waste an incredible amount of time. A phone interview enables you to assess the skill set of a potential employee without wasting time by picking him up, getting a security badge, booking a conference room etc. A phone interview is also good for the candidate since he/she doesn’t have to travel or dress up to do the interview.
Some things are difficult to ask over the phone but if the candidate looks (or should that be sounds) good then you can ask those questions when you bring the person in. Some people will prepare for a phone interview by having all their books and notes in front of them. They will ask you to repeat the question and while you do so you can hear them flipping pages frantically. So you might be able to cheat on the phone interview but be assured that if you do not know your stuff that you will fall flat on your face on a face to face interview (no pun intended).
One thing I never understood is the fact that it takes a person one minute to answer a question. You either know or don’t know the question. Keep your answers concise, do not spend 3 minutes explaining to me what the difference is between a clustered and non clustered index.
I had to reword my questions slightly because when I asked a question like “Do you know what the difference is between a clustered index and a non clustered index?” some people would reply “yes”. Because of that I changed the question to “Describe what the difference is between a clustered index and a non clustered index?”
Do not shoot yourself in the foot by giving me additional information which is wrong. I asked for the fastest way to empty a table. Almost every single person who knew about truncate added that you cannot rollback a truncate statement. I wrote about that myth a couple of months ago: SQL Myth: Truncate Cannot Be Rolled Back Because It Is Not Logged
I tend to ask between 20 and 40 questions, if I see the candidate’s skill is not good enough I don’t ask everything. Some of the questions are esoteric but I simply ask these questions to get a feel of the overall skill level; it doesn’t matter if they answer these wrong. You can find a list of question here: How Well Do You Interview And Do You Use Wizard Driven Programming?
Here are some interesting answers from the interviews.
Almost every single person answered that an index scan is better than an index seek.
There were several people with SQL Server 2005 experience, these people couldn’t name one single new thing introduced in SQL Server 2005. I asked about windowing functions, DMVs, pivot, apply and more, this was all Greek to them. One person had on her resume that she developed an app in SQL Server 2005. When I asked about her experience she told me she just started to read about SQL Server 2005. This is a big show stopper, sometimes headhunters/recruiters will tell you to just add it to your resume, I wouldn’t do it because it makes you look bad. If the SQL Server 2005 experience is not true what else could be made up? One person had on his resume that he optimized complex stored procedures, when I asked how he did it, he replied that he only selected the rows he needed instead of the whole table. This obviously didn’t answer my question.
That is it for the phone interview, part 2 will be up in a day or two.
EURO 2008 draw
My picks below
Group A: Switzerland, Turkey, Portugal, Czech Republic
1. Portugal, Czech Republic.
Group B: Austria, Poland, Germany, Croatia
1.Croatia, 2. Germany.
Group C: Holland, France, Romania, Italy
1. France, 2. Holland.
Group D: Greece, Russia, Spain, Sweden
1. Spain, 2. Greece.
Group A: Switzerland, Turkey, Portugal, Czech Republic
1. Portugal, Czech Republic.
Group B: Austria, Poland, Germany, Croatia
1.Croatia, 2. Germany.
Group C: Holland, France, Romania, Italy
1. France, 2. Holland.
Group D: Greece, Russia, Spain, Sweden
1. Spain, 2. Greece.
Saturday, December 01, 2007
Screencast: SQL Server 2008 - Table valued parameters
If you have to insert more than one row of data in a Table, you end up executing the insert statement / stored procedure as many times for each row, with Table-valued parameters you can send multiple rows of data to a single TSQL statement or stored procedure without creating temp tables or doing multiple round trips.
Table-valued parameters are a new parameter type in SQL Server 2008 and are declared by using user-defined table types.
Watch the screencast(SWF)
Watch the screencast(WMV)
Table-valued parameters are a new parameter type in SQL Server 2008 and are declared by using user-defined table types.
Watch the screencast(SWF)
Watch the screencast(WMV)
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