SQL Server Code,Tips and Tricks, Performance Tuning

Tuesday, January 02, 2007

Monday, January 01, 2007

Dynamic Search Conditions In T-SQL Has Been Updated

SQL Server MVP Erland Sommarskog has updated his Dynamic Search Conditions in T-SQL article on 2006-12-27.

Here is what is new

Added a section on a new fascinating hybrid method built on inline table functions, discovered by SQL Server MVP Marcello Poletti.
Put back the section Using EXEC() from the appendix.
Added new section When Caching Is Really Not What You Want.
Some general review on comments of performance.

So what are you waiting for? It is a new year and there is new stuff to read.

Dynamic Search Conditions in T-SQL

And yes I will post my new years resolutions sometime this week

Sunday, December 31, 2006

The Road to Hell By Chris Rea Or Highway to Hell By AC/DC

So here is my last goofy post of the year, I will have some posts that have at least something to do with SQL and databases from tomorrow on. I just happened to hear both of these songs today and since their titles are so similar I decided to do a little poll. So the question is which of these two do you prefer?

The Road to Hell by Chris Rea from the album Road to Hell
Or
Highway to Hell by AC/DC from the album Highway to Hell

The title Highway to Hell has nothing to do with Satanism (Malcolm once said "me mum would kill me for that!"). The title came after a reporter asked AC/DC if they could describe what life was like constantly touring around the globe. Angus replied that it was "a highway to Hell", and the name stuck

Believe it or not I will pick The Road to Hell as my favorite song. If you asked me yesterday I would have picked Highway to Hell; maybe I am not angry enough today and am in a pleasant mood, It is New Years Eve after all.
The first four songs on Highway to Hell are the best, I actually prefer Walk All Over You over Highway to Hell. While Highway to Hell is a hardrock song The Road to Hell is not; you will find that it reminds you of Dire Straits when listening to it (I believe Mark Knopfler plays guitar on the song)

The Road to Hell Track listing
------------------------------------
The Road to Hell (Pt. 1)
The Road to Hell (Pt. 2)
You Must Be Evil
Texas
Looking for a Rainbow
Your Warm and Tender Love
Daytona
That's What They Always Say
I Just Wanna Be With You
Tell Me There's a Heaven

Highway to Hell Track listing
---------------------------------------
Highway to Hell
Girls Got Rhythm
Walk All Over You
Touch Too Much
Beating Around the Bush
Shot Down in Flames
Get It Hot
If You Want Blood (You've Got It)
Love Hungry Man
Night Prowler

This was of course the last album that AC/DC recorded with Bon Scott; he died 6 months later. The cause of death listed on his death certificate was "Acute alcoholic poisoning" and the verdict of the inquest "Death by misadventure". After Bon Scott's death the band hired Johnson as their new lead singer. They recorded Back in Black in 1980 which would become the fourth best-selling album in the United States, tied with Billy Joel's Greatest Hits Vol. 1 & II with 21 million copies sold

So which one do you prefer?

Friday, December 29, 2006

SQL Server 2005 SP2 Backup With Vardecimal Enabled Can't Be Restored On SQL Server 2005 SP1 or Earlier

SQL Server 2005 SP2 introduces the Vardecimal storage format. The Vardecimal storage format is a new storage format to store decimal/numeric data. This new storage format is not understood by SQL Server 2005 or SQL Server 2005/SP1. Just like you cannot attach a SQL Server 2005 database to SQL Server 2000, attaching/restoring a SQL Server 2005/SP2 database that has been enabled for Vardecimal storage format to earlier versions of SQL Server 2005 will fail. SQL Sever implements this by incrementing the database version number when the database is enabled for Vardecimal storage format. When you disable Vardecimal storage format on a database, its database version is decremented so that the database can now be attached to earlier versions of SQL Server 2005.

Read more about this and what the implications are here: http://blogs.msdn.com/sqlserverstorageengine/archive/2006/12/29/vardecimal-storage-format-and-its-implications-on-backup-recovery.aspx

Thursday, December 28, 2006

Guess Who Gave This Answer In A Newsgroup?

Try to guess who gave this answer. Here is a small hint, the person looks like Anton Szandor LaVey

Question: I guess the key question for me is, can this be done entirely in SQL?

Answer: The answer is always "Yes, we can do it in SQL!"

The right answer is "But, like a size 26 thong, just because you can
does not mean you should!"

Google around for "Bin packing" and/or "Knapsack" problems on some math
websites. This is a known NP-complete problem. In English, it means
that the only way to solve it is to try all possible combinations, so
the execution time grows fastrer than any polynominal expression (i.e
think about factorials or worse).

There are often several valid solutions, too. Being a set-oriented
language, SQL will attempt to find the set of ALL solutions. And run
forever.

This is a job for a procedure (yes, [name here] is saying nice thing about
procedural code!) which will stop at the first usable answer, even if
it is not optimal. Now you have to pick your algorithm. This is
usually the Greedy algorithm ("grab the biggest bite you can and add it
to the answer; see if you met the goal; if not, repeat") modified to do
some back tracking.

So who gave this answer?

Wednesday, December 27, 2006

Sweet Child O' Mine By Guns N' Roses Or Child in Time By Deep Purple?

Yesterday we talked about Whole Lotta Love and whole Lotta Rosie today we are talking about Sweet Child O' Mine and Child In Time. So which is your favorite?

Sweet Child O' Mine by Guns N' Roses from the album Appetite for Destruction
Child in Time by Deep Purple from the album Deep Purple in Rock

This is a very tough pick for me because I love both songs but I would have to go for Sweet Child O' Mine. This song is perfect in every way from the vocals to the guitar solo to the introduction's famous D-flat based riff. The lyrics were written by Axl Rose as a love letter to his girlfriend at the time Erin Everly. No matter how many times I listen to the song it never bores me; something I can’t say about Paradise City; I just can’t stand that song anymore

Child in time is a song that is over 10 minutes long; It starts slowly with only an organ then builds up to a faster pace and then stops abruptly to start over again. Guitarist Ritchie Blackmore solo is just amazing and Ian Gillan’s voice goes from quiet singing to loud screaming. If you never heard this song I urge you to check it out.

Lyrically, the song is deep and dark; here are the lyrics:
Sweet child in time,
You'll see the line.
The line that's drawn between,
The good and the bad.
See the blind man,
He's shooting at the world.
The bullets flying,
Mmm... they're taking toll.
If you've been bad,
Lord I bet you have.
And youve not been hit,
You've not been hit by flying lead.
You'd better close your eyes,
You'd better bow your head.
Wait for the ricochet...

I have at least 3 versions of this song; the original, the live version from Made In Japan and the live version from Scandinavian Nights.

My favorite Guns N' Roses songs:
Mr. Browstone
Live and Let Die
Don't Cry
Civil War
Knockin' on Heaven's Door
You Could Be Mine
It's So Easy
Nightrain
Out Ta Get Me
Mr. Brownstone
My Michelle
Think About You
Sweet Child O' Mine
You're Crazy

My favorite Deep Purple songs:
Child In Time
Smoke On The Water
Hush
Soldier Of Fortune (David Coverdale is the singer on this one)
Speed King (the longer version with crazy guitar intro)

So which are your favorites?

Tuesday, December 26, 2006

sys.dm_db_session_space_usage

Okay so today we will talk about the sys.dm_db_session_space_usage dynamic management view.
This is the third dynamic management view that I have covered; a list if all of them and the date that I covered some of them can be found below

http://sqlservercode.blogspot.com/2006/08/dynamic-management-views-blog-post.html

Before we start here are a couple of remarks

IAM pages are not included in any of the allocation or deallocation counts reported by this view.

Page counters are initialized to zero (0) at the start of a session. The counters track the total number of pages that have been allocated or deallocated for tasks that are already completed in the session. The counters are updated only when a task ends; they do not reflect running tasks.

A session can have multiple requests active at the same time. A request can start multiple threads, tasks, if it is a parallel query.

Here is some information about the columns in this view

session_id
smallint
Session ID.
-- session_id maps to session_id in sys.dm_exec_sessions.

database_id
smallint
Database ID.

user_objects_alloc_page_count
bigint
Number of pages reserved or allocated for user objects by this session.

user_objects_dealloc_page_count
bigint
Number of pages deallocated and no longer reserved for user objects by this session.

internal_objects_alloc_page_count
bigint
Number of pages reserved or allocated for internal objects by this session.

internal_objects_dealloc_page_count
bigint
Number of pages deallocated and no longer reserved for internal objects by this session.

First we will talk about user objects

User Objects
The following objects are included in the user object page counters:

User-defined tables and indexes
System tables and indexes
Global temporary tables and indexes
Local temporary tables and indexes
Table variables
Tables returned in the table-valued functions

SELECT *
FROM sys.dm_db_session_space_usage
WHERE session_id = @@spid

Values in the columns
--------------------------------------
user_objects_alloc_page_count =0
user_objects_dealloc_page_count = 0
internal_objects_alloc_page_count = 0
internal_objects_dealloc_page_count = 0

CREATE TABLE #temp(id VARCHAR(MAX))
INSERT #TEMP VALUES(REPLICATE('a',25000))
INSERT #TEMP VALUES(REPLICATE('b',25000))
INSERT #TEMP VALUES(REPLICATE('c',25000))
INSERT #TEMP VALUES(REPLICATE('d',25000))
INSERT #TEMP VALUES(REPLICATE('e',25000))

SELECT *
FROM #temp

SELECT *
FROM sys.dm_db_session_space_usage
WHERE session_id = @@spid

user_objects_alloc_page_count =5
user_objects_dealloc_page_count = 0
internal_objects_alloc_page_count = 0
internal_objects_dealloc_page_count = 0

DROP TABLE #temp

SELECT *
FROM sys.dm_db_session_space_usage
WHERE session_id = @@spid

Values in the columns
--------------------------------------
user_objects_alloc_page_count =5
user_objects_dealloc_page_count = 5
internal_objects_alloc_page_count = 0
internal_objects_dealloc_page_count = 0

CREATE TABLE #temp(id VARCHAR(MAX))
INSERT #TEMP VALUES(REPLICATE('a',25000))
INSERT #TEMP VALUES(REPLICATE('b',25000))
INSERT #TEMP VALUES(REPLICATE('c',25000))
INSERT #TEMP VALUES(REPLICATE('d',25000))
INSERT #TEMP VALUES(REPLICATE('e',25000))

SELECT *
FROM #temp

SELECT *
FROM sys.dm_db_session_space_usage
WHERE session_id = @@spid

Values in the columns
--------------------------------------
user_objects_alloc_page_count =10
user_objects_dealloc_page_count = 5
internal_objects_alloc_page_count = 0
internal_objects_dealloc_page_count = 0

TRUNCATE TABLE #temp

SELECT *
FROM sys.dm_db_session_space_usage
WHERE session_id = @@spid

Values in the columns
--------------------------------------
user_objects_alloc_page_count =10
user_objects_dealloc_page_count = 10
internal_objects_alloc_page_count = 0
internal_objects_dealloc_page_count = 0

DROP TABLE #temp1

so those were the use objects now we will talk about internal objects

Internal Objects
Internal objects are only in tempdb. The following objects are included in the internal object page counters:

Work tables for cursor or spool operations and temporary large object (LOB) storage
Work files for operations such as a hash join
Sort runs

--Create the tables
CREATE TABLE #temp1(id INT, SomeCol VARCHAR(MAX))
INSERT #TEMP1 VALUES(1,REPLICATE('a',25000))
INSERT #TEMP1 VALUES(2,REPLICATE('b',25000))
INSERT #TEMP1 VALUES(3,REPLICATE('c',25000))
INSERT #TEMP1 VALUES(4,REPLICATE('d',25000))
INSERT #TEMP1 VALUES(5,REPLICATE('e',25000))

CREATE TABLE #temp2(id INT, SomeCol VARCHAR(MAX))
INSERT #TEMP2 VALUES(1,REPLICATE('a',25000))
INSERT #TEMP2 VALUES(2,REPLICATE('b',25000))
INSERT #TEMP2 VALUES(3,REPLICATE('c',25000))
INSERT #TEMP2 VALUES(4,REPLICATE('d',25000))
INSERT #TEMP2 VALUES(5,REPLICATE('e',25000))

--Do a sort operation
SELECT *
FROM#TEMP2 t2
JOIN #TEMP1 t1 ON t1.id = t2.id
ORDER BY t1.id,t1.SomeCol,t2.id,t2.SomeCol

--Check the view
SELECT *
FROM sys.dm_db_session_space_usage
WHERE session_id = @@spid

Values in the columns
--------------------------------------
user_objects_alloc_page_count =20
user_objects_dealloc_page_count = 10
internal_objects_alloc_page_count = 16
internal_objects_dealloc_page_count = 8

What is this dmv useful for? You can use it to to help you diagnose and troubleshoot problems caused by insufficient disk space in the tempdb database.

The following error messages indicate insufficient disk space in the tempdb database. These errors can be found in the SQL Server error log, and may also be returned to any running application.

1101 or 1105
Any session must allocate space in tempdb.

3959
The version store is full. This error usually appears after a 1105 or 1101 error in the log.

3967
The version store is forced to shrink because tempdb is full.

3958 or 3966
A transaction cannot find the required version record in tempdb.

Some of these queries that you can use can be found here: Troubleshooting Insufficient Disk Space in tempdb

Whole Lotta Rosie By AC/DC or Whole Lotta Love By Led Zeppelin?

I got a new MP3 player from my sister in law for Christmas and have been listening to some good old R & R

So the question is which of these similar named songs do you prefer?
Whole Lotta Rosie by AC/DC with Bon Scott from the album Let There Be Rock.
Whole Lotta Love by Led Zeppelin from the album Led Zeppelin II.

Between these two my pick is Whole Lotta Rosie by AC/DC and I think that this is still my favorite AC/DC song.

My favorite Led Zeppelin song is not Whole Lotta Love but one of these
Since I've Been Loving You from Led Zeppelin III
Black Dog from Led Zeppelin IV
Over the Hills and Far Away from Houses of the Holy
Travelling Riverside Blues from the Led Zeppelin Box Set

I am still undecided on the Led Zep favorite. Which is your favorite Led Zep song? And no Stairway to Heaven is not allowed as your pick

Thursday, December 21, 2006

Display 1 When Any Column Is 1 And 0 Otherwise by Using SIGN, SUM Or (Bitwise OR)

You have three columns; if any of the columns is 1 you want to display 1 if they are all 0 you want to display 0. how can you do that?
there are basically three ways to do this
1 SUM
2 SIGN
3 | (Bitwise OR)

Here are the examples

--create table and insert rows
CREATE TABLE #test (test_A INT,test_B INT,test_C INT)

INSERT INTO #test VALUES(0,0,0)
INSERT INTO #test VALUES(1,0,0)
INSERT INTO #test VALUES(0,1,0)
INSERT INTO #test VALUES(0,0,1)
INSERT INTO #test VALUES(0,1,1)
INSERT INTO #test VALUES(1,1,1)

First we will display 0 if all columns are 0; if any of the columns is 1 then we will display a one

--Using SIGN
SELECT SIGN(test_A+test_B+test_C) ,*
FROM #test

--Using (Bitwise OR)
SELECT (test_A | test_B | test_C),*
FROM #test

--Using Sum
SELECT CASE SUM(test_A + test_B + test_C)
WHEN 0 THEN 0 ELSE 1 END, *
FROM #test
GROUP BY test_A , test_B , test_C

Now let's say we want to display 1 if all the values are 1.
we can do that by using &; this is the Bitwise AND operator
--Using (Bitwise AND)
SELECT (test_A & test_B & test_C),*
FROM #test

-- SUM can also be used
SELECT CASE SUM(test_A + test_B + test_C)
WHEN 3 THEN 1 ELSE 0 END, *
FROM #test
GROUP BY test_A , test_B , test_C

Now let's reverse the process and display 0 if any of the columns are 1 and 1 if all the columns are 0.
We have to use CASE to accomplish this

--Using CASE with SIGN
SELECT CASE SIGN(test_A+test_B+test_C)
WHEN 1 THEN 0 ELSE 1 END, *
FROM #test

--Using CASE with Bitwise OR
SELECT CASE (test_A | test_B | test_C)
WHEN 1 THEN 0 ELSE 1 END, *
FROM #test

--Using SUM with CASE
SELECT CASE SUM(test_A + test_B + test_C)
WHEN 0 THEN 1 ELSE 0 END, *
FROM #test
GROUP BY test_A , test_B , test_C

Here is some additional stuff, add this row and run the queries again
INSERT INTO #test VALUES(1,NULL,1)

What happens when you run this?

SELECT SIGN(test_A+test_B+test_C) ,*
FROM #test

A NULL is returned; If you have NULLS in your table then you might want to use COALESCE

SELECT SIGN(test_A+COALESCE(test_B,0)+test_C) ,*
FROM #test

Wednesday, December 20, 2006

SQL Server 2005 Will Be Supported On Vista And Windows Server Longhorn

Don't get scared of those people at Badvista.org

Microsoft announced on September 27, 2006 that SQL Server 2005 would be supported on Vista This is just more FUD from Stallman & Co. However you must have service Pack 2 installed for it to run. From the site:

"In an effort to provide customers with more secure products, Microsoft Windows Server "Longhorn" and Microsoft Windows Vista will only support SQL Server 2005 Service Pack 2 (SP2) or later when it becomes available. Earlier versions of SQL Server, including SQL Server 2000 (all editions including Desktop Engine edition, a.k.a MSDE), SQL Server 7.0, and SQL Server 6.5, will not be supported on Windows Server "Longhorn" or Windows Vista. Customers running applications with these earlier versions of SQL Server should consider evaluating and upgrading to SQL Server 2005, which was designed to take advantage of the upcoming security and performance enhancements in the operating environment."

You can read the whole story here

You can test SQL Server 2005 Service Pack 2 - Community Technology Preview (CTP) December 2006 right now

SQL Server 2005 Service Pack 2 - Community Technology Preview (CTP) December 2006 Available For Download

That's right it's here. Download it now and play around with vardecimal and custom reports for Management Studio

http://www.microsoft.com/downloads/details.aspx?FamilyID=d2da6579-d49c-4b25-8f8a-79d14145500d&DisplayLang=en

Tuesday, December 19, 2006

How Well Do You Interview And Do You Use Wizard Driven Programming?

We were interviewing people for developer and architect positions. The developer position required about 5 years C# and SQL Server. We got a couple of good candidates but some of them were really terrible. They claim SQL server experience since 1998 but don't know what a clustered index is or they can not name even one isolation level. There were people who had 10 years experience in web development but could not explain what MVC (Model-view-controller) is or name a design pattern. People created webservices but did not know what a WSDL is?????

You see this is the problem I have with WDP (Wizard Driven Programming); It's okay to use wizards but you HAVE to know what is going on behind the scenes. It's okay to use Enterprise Manager but you have to know how to do the same thing in Query Analyzer. If you never write your own scripts you will sooner or later come to a shop where they don't use these tools and changes have to be submitted via scripts. Not only do you have to script everything you also have to provide back-out scripts in case something goes wrong.

So here are some of the questions I asked; with 5 years experience I think you should not miss more than two (probably traceflag 1204 and parameter sniffing questions)

Let me know how many you couldn't get without looking them up

What is normalization
What is the fastest way to empty a table
what is a deadlock
Can you give an example of creating a deadlock
How do you detect deadlocks
What is an audit trail
what is an identity column
How do you return an identity value from a table
How do you return an identity value from a table with a trigger
How many bytes can you fit in a row, do you know why
What is a clustered index
How many clustered indexes per table
How many nonclustered indexes per table
what is an execution plan
Between index scan, index seek and table scan; which one is fastest and which one is slowest
How do you return a value from a proc
How do you return a varchar value from a proc
If I have a column that will only have values between 1 and 250 what data type should I use
How do you enforce that only values between 1 and 10 are allowed in a column
How to check for a valid date
Which date format is the only safe one to use when passing dates as strings
How do you suppress rows affected messages when executing an insert statement
Can you name the 4 isolation levels in SQL Server 2000
How would you select all last names that start with S
How would you select all rows where the date is 20061127
What is horizontal partitioning
What does schemabinding do
How do you test for nulls
Name some differences between isnull and coalesce
What is a temp table
what is the difference between a local and global temporary table
If you create a local temp table and then call a proc is the temp table available inside the proc
What is referential integrity
what is the fastest way to populate a table (performance wise)
using the method above what can you do to make it even faster
What data type should you use to store monetary values
What is a cascade delete
Name a couple of types of joins
What is a SQL injection
What is parameter sniffing
Name 2 differences between a primary key and UNIQUE Constraints
How do you ensure that SQL server will use an index
What does option fast (10) do
What is the difference between union and union all
What does trace flag 1204 do

Sunday, December 17, 2006

BadVista: The Worst FUD You Will Ever Read.... St. Ignucious Has Gone Wild

Richard Stallman (RMS, St. Ignucious ) is at it again. let's see what the site says:

The Free Software Foundation (FSF) today launched BadVista.org, a campaign
with a twofold mission of exposing the harms inflicted on computer users by the
new Microsoft Windows Vista and promoting free software alternatives that
respect users' security and privacy rights.
“Vista is an upsell masquerading
as an upgrade. It is an overall regression when you look at the most important
aspect of owning and using a computer: your control over what it does. Obviously
MS Windows is already proprietary and very restrictive, and well worth
rejecting. But the new 'features' in Vista are a Trojan Horse to smuggle in even
more restrictions. We'll be focusing attention on detailing how they work, how
to resist them, and why people should care”, said FSF program administrator John
Sullivan.

More interesting is the piece of garbage that they link to: 25 Shortcomings Of Vista

Here are some of the 'gems'

1. SMB2: Vista introduces a new variant of the SMB protocol called SMB2, which may pose problems for those connecting to non-Microsoft networks, such as Samba on Linux.
--Speculation and pure FUD

7. Five Versions: The array of Vista editions could prove to be three too many, and upgrades between versions remain an unknown.
8. Activation: The need to activate the product via the Web could prove to be a time-waster during mass deployments.
--Could prove? Could prove? Who writes this stuff? For mass deployments there is something called Key Management Service

Key Management Service
Your organization can host the Key Management Service (KMS) internally to automatically activate computers running Windows Vista. To use the KMS, you must have a minimum of 25 computers running Windows Vista that are connected together. Computers that have been activated through KMS will be required to reactivate by connecting to your organization's network at least every six months.

Currently the KMS software runs on a local computer running Windows Vista or the Microsoft Windows Server Code Name "Longhorn" operating system. In the future, it will run on the Microsoft Windows Server 2003 operating system.

9. Storage Space: With Vista taking as much as 10 Gbytes of hard drive space, big and fast hard drives will be a must.
--Last time I checked you can't really buy anything less than 100GB

10. Backup: See No. 9. Backing up desktops will take a great deal of space.
--So backup only your personal data.

18
Buried Controls
Many options and controls are further buried, requiring a half-dozen mouse clicks or more to get to. Network settings and display settings are offenders here.
--Some people said the same thing in WinXP, until they realized there is also a classic view. Vista has this classic view also.

19. Installation Can take hours on some systems. Upgrades are even slower.
--This is BS; it should not take more than 30 minutes unless you got a pirated copy on 1500 floppy discs

20. HHD Hybrid Hard Drives. These are potentially a huge performance booster, but there's little information and support is available (even though should be available).
--Since when is having an emerging technology that will boost performance a shortcoming?

#25:
WordPadAbility to open .doc files has been removed.
--Hahahahahaha who wrote this piece of crap. You either use Word or OpenOffice

The writer of this article is Frank J. Ohlhorst send him an email if you want to tell him what you think

Friday, December 15, 2006

Three Ways To Display Two Counts From a Table Side By Side

This question came up on tek-tips.

I want to count the CA and the UT states from the authors table and output this in different columns named CaCount and UtCount

CaCount UtCount
----------- -----------
15 2

How do you do such a thing? To display the following is very easy

state StateCount
----- -----------
CA 15
UT 2

You just do a count and group by

SELECT state,COUNT(*) AS StateCount
FROM authors
WHERE state in ('CA', 'UT')
GROUP BY state

How do we display them side by side? We can do this 3 different ways
1 stick the count in variables
2 run the count twice a s a separate query
3 sum with case

USE PUBS
GO

--stick the count in variables
DECLARE @UtCount INT
DECLARE @CaCount INT

SELECT @UtCount = COUNT(*) FROM authors WHERE state ='UT'
SELECT @CaCount = COUNT(*) FROM authors WHERE state ='CA'

SELECT @CaCount AS CaCount,@UtCount AS UtCount

--run the count twice as a separate query
SELECT (SELECT COUNT(*) FROM authors
WHERE state ='CA') AS CaCount,
(SELECT COUNT(*) FROM authors WHERE state ='UT') AS UtCount

--sum with case
SELECT SUM(CASE state WHEN 'CA' THEN 1 ELSE 0 END) AS CaCount,
SUM(CASE state WHEN 'UT' THEN 1 ELSE 0 END) AS UtCount
FROM authors

If you look at the execution plan then you will see that the best option is the third one (sum with case). The third option only queries the table once instead of twice like the other two solutions and will thus be twice as fast
So keep that in mind when you have to do such a query next time

[edit]
Oracle Version
jbjornson left the Oracle version in a comment; I decided to add it to the post. I don't know about the syntax coloring on Oracle/TOAD so you are getting a black and white only ;-(

--run the count twice as a separate query
SELECT CA.caCount, UT.UtCount
FROM (SELECT COUNT(*) as CaCount FROM authors) WHERE state ='CA') CA,
(SELECT COUNT(*) FROM authors WHERE state ='UT') UT

--sum with case
SELECT SUM(decode(state, 'CA', 1, 0)) AS CaCount,
SUM(decode(state, 'UT', 1, 0)) AS UtCount
FROM authors
[/edit]

Visual Studio 2005 Service Pack 1 (SP1) Released

Visual Studio 2005 Service Pack 1 (SP1) has been released. From the site:

Service Pack 1 addresses issues that were found through a combination of customers and partner feedback, as well as internal testing. The issues addressed range in severity from places where the syntax coloring was incorrect to customer reported crashes in various scenarios. In some areas, more than 50% of the bugs addressed were reported by customers through the MSDN Product Feedback Center and Microsoft Connect. Overall, Service Pack 1 offers customers improvements in responsiveness, stability and performance for Visual Studio 2005.

Through further advancement and feedback, Service Pack 1 also provides over 70 improvements for common development scenarios including:

New processor support (e.g., Core Duo) for code generation and profiling

Performance and scale improvements in Team Foundation Server

Team Foundation Server integration with Excel 2007 and Project 2007

Tool support for occasionally connected devices and SQL Server Compact Edition

Additional support for project file based Web applications

Windows Embedded 6.0 platform and tools support

Get it here

Wednesday, December 13, 2006

Index Build Strategy In SQL Server

The Tips, Tricks, and Advice from the SQL Server Query Processing Team blog has 3 really good posts about Index Build strategy in SQL Server. You should definitely read these to really understand how to implement that. Here are the links:
Index Build strategy in SQL Server - Part 1: offline, serial, no partitioning

Index Build strategy in SQL Server - Part 2: Offline, Parallel, No Partitioning

Index Build strategy in SQL Server - Part 2: Offline, Parallel, No Partitioning (Non stats plan (no histogram))

Problems With ROW_NUMBER() In A WHERE Clause

This is a question that came up today. A person had a query like this

USE AdventureWorks
GO

SELECT
ROW_NUMBER() OVER (ORDER BY addressline1) AS rowNum,
addressline1,
city
FROM person.address
WHERE rowNum > 3;

That gave the following error
Server: Msg 207, Level 16, State 1, Line 6
Invalid column name 'rowNum'.

What you have to do is use Common Table Expressions or use a subquery. Below are both methods.

--Subquery
SELECT * FROM ( SELECT
ROW_NUMBER() OVER (ORDER BY addressline1) AS rowNum,
addressline1,
city
FROM person.address) AS x
WHERE rowNum > 3;

--CTE
WITH x (rowNum,addressline1,
city) AS
(SELECT
ROW_NUMBER() OVER (ORDER BY addressline1) AS rowNum,
addressline1,
city
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Tuesday, December 12, 2006

SQL Server 2005 Practical Troubleshooting: The Database Engine Is Shipping!

Amazon is shipping SQL Server 2005 Practical Troubleshooting: The Database Engine. This is a must have for all SQL developers who run into any kind of problems with SQL Server 2005

For all of you who did not read my interview with the editor of this book Ken Henderson; you can find that here; Ken describes the target audience for the book the most important chapters for customers who have performance problems and much more

A sample chapter is available: Chapter 4 Procedure Cache Issues

About the book:
Paperback: 456 pages
Publisher: Addison-Wesley; 1ST edition
Language: English
ISBN: 0321447743

Contents
Preface
Chapter 1 Waiting and Blocking Issues
Chapter 2 Data Corruption and Recovery Issues
Chapter 3 Memory Issues
Chapter 4 Procedure Cache Issues
Chapter 5 Query Processor Issues
Chapter 6 Server Crashes and Other Critical Failures
Chapter 7 Service Broker Issues
Chapter 8 SQLOS and Scheduling Issues
Chapter 9 Tempdb Issues
Chapter 10 Clustering Issues
Index

Amazon Links:

Visual Studio Team Edition for Database Professionals links

By now you know that Visual Studio Team Edition for Database Professionals has been released. But do you know all the links to the newsgroup, documentation and download page? No? No problem here are the links:

Download Link
The product is available on the MSDN subscribers site, or you can download the trial version from he following URL :http://www.microsoft.com/downloads/details.aspx?FamilyId=7DE00386-893D-4142-A778-992B69D482AD&displaylang=en
For the trial version, you still need an installed copy of Visual Studio 2005 Team Suite which can be either a trial or a licensed version

Documentation
Team Edition for Database Professionals

Forum
Visual Studio Team System - Database Professionals

Visual Studio 2005 Team Edition for Database Professionals Site
Data Dude