Thursday, June 29, 2006

List DDL Triggers By Using The sys.triggers Catalog View

How do you list DDL triggers in SQL Server 2005? It's very easy you just query the sys.triggers catalog view. Let's try an example

USE adventureworks
GO

--Create our trigger
CREATE TRIGGER trDropTable
ON DATABASE
FOR DROP_TABLE
AS
PRINT 'You can not drop tables'
ROLLBACK
GO


--Create the table
CREATE TABLE abc(id INT)
GO

--Let's drop the table
DROP TABLE abc
GO

Our trigger works because the following message is displayed after we tried to drop the table

You can not drop tables
Msg 3609, Level 16, State 2, Line 1
The transaction ended in the trigger. The batch has been aborted.


In order to list DDL triggers you need to use parent_id = 0
SELECT * FROM sys.triggers
WHERE parent_id = 0

In order to list DML triggers you need to use parent_id <> 0
SELECT * FROM sys.triggers
WHERE parent_id <> 0

And if you want to list all triggers you can just ommit the WHERE clause

Wednesday, June 28, 2006

Murphy's Law And SQL Server

Why do things break the moment that the person who handles something is on vacation?
Here is the full story. A co-worker goes on vacation, he has his work on a specific server, this server is in our lab and not on the MCN (Mission Critical Network). First let me tell you that we are considered ‘renegades’ and that we don’t get operation support for some of our machines because we don’t use corporate standards and we need full control over our machines.
Anyway the server worked fine for 2 years, co-worker goes on vacation to Japan and the very next day I am getting crazy errors like can not use ad-hoc queries use linked server instead???? I click on the linked server and get OLEDB FoxPro driver missing errors? Fine let’s restart, simple enough right? Wrong! After hitting stop from Service Manager the status is ‘stopping’, after 20 minutes it is still ‘stopping’
Mmm I don’t want to to a hard reboot because I can corrupt all the databases and I don’t even know where half of the backups are (I don’t use this server). Okay let’s try NET STOP MSSQLSERVER. Nope application is in transition and can not be stopped error. Then it occurred to me that maybe we got hit by the slammer worm. Since it’s stopping I can not execute serverproperty so I right click on the sqlserver.exe file and look up the version number. It’s 2039, good that’s SP4. Then I hit restart from the start button and it restarted and everything was fine.

So what is Murphy's Law? Here is the Wikipedia link in case you want to know
http://en.wikipedia.org/wiki/Murphy's_law

Monday, June 26, 2006

DELETE and Subquery (IN) Problem

When you have a DELETE used with an IN (subquery) all rows will be deleted if your subquery is wrong
What do I mean by this? Let's say you have a table named Table1 with 1 column, the name of that column is Col1
When you do SELECT ID FROM Table1 you get an error.
However when you do
DELETE FROM TEST1 WHERE ID IN
(SELECT ID FROM Table1)
all rows are deleted


Let's start with our test

--Create tables and data
CREATE TABLE TEST1 (ID INT)
GO
CREATE TABLE TEST2 (BLA INT)
GO

INSERT INTO TEST1 VALUES(1)
INSERT INTO TEST1 VALUES(2)
INSERT INTO TEST1 VALUES(3)
INSERT INTO TEST2 VALUES(1)
GO

-- The following will raise an error
SELECT ID FROM TEST2 WHERE BLA = 1
GO
--Server: Msg 207, Level 16, State 3, Line 1
--Invalid column name 'ID'.


-- The following statement will delete the entire table
DELETE FROM TEST1 WHERE ID IN
(SELECT ID FROM TEST2 WHERE BLA = 1)
GO
--(3 row(s) affected)


--One way of doing it
DELETE FROM TEST1 WHERE ID IN
(SELECT B.ID FROM TEST2 B WHERE BLA = 1)
--Server: Msg 207, Level 16, State 3, Line 1
--Invalid column name 'ID'.



--Another way
DELETE FROM TEST1 WHERE exists
(SELECT * FROM TEST2 B WHERE BLA = 1 AND b.ID =TEST1.ID)
--Server: Msg 207, Level 16, State 3, Line 1
--Invalid column name 'ID'.

Sunday, June 25, 2006

The Difference Between Unique Constraint And Unique Index

Do you know the the difference between an unique constraint, and an unique index?
If you do not or if you are not sure then make sure you read the following article:
Unique constraint, or unique index

That article also has a link on how to do selective uniqueness handling

Thursday, June 22, 2006

SQL Server Datetime Datatypes

Since I am kind of busy (Work, House, FIFA World Cup Soccer/Football) I said that I would post links to great SQL Server stuff by other people, so here is a gem that you should definitely read if you have any questions about dates in SQL Server. The name of this page is "The ultimate guide to the datetime datatypes" and it is written by SQL Server MVP Tibor Karaszi and it covers the following things.


Date and time datatypes in SQL Server
Date and time formats
Date and time formats for input
Recommendations for input
Warnings and common misconceptions
Output of datetime values
Searching for datetime values
Getting rid of the time portion
Tip: Always set the time to the same value
Other tips, from SQL Server MVP Steve Kass
Why is 1753 the earliest date for datetime?
References and reading tips

So what are you waiting for, click on the link below?

http://www.karaszi.com/SQLServer/info_datetime.asp

Wednesday, June 21, 2006

3.5 Ways To Show Stored Procedure Code In SQL Server 2005

There are four (more on that later) ways in SQL Server 2005 to get the create procedure script. Why does the title say 3.5, well that is because the INFORMATION_SCHEMA.ROUTINES view only returns the first 4000 characters. So if your proc is 5000 characters then you are out of luck (not really since you can use the other 3 methods)

So let’s start, we will be using the uspGetBillOfMaterials stored procedure in the AdventureWorks database

sp_helptext
This is the same as in SQL server 2000 nothing new here

sp_helptext 'dbo.uspGetBillOfMaterials'



sys.sql_modules
So this is a new view in SQL Server 2005, what we need is the definition column

SELECT definition
FROM sys.sql_modules
WHERE object_id = OBJECT_ID('dbo.uspGetBillOfMaterials')



OBJECT_DEFINITION()
This is a new function in SQL Server 2005, just combine it with OBJECT_ID to get the proc code back

SELECT OBJECT_DEFINITION (OBJECT_ID('dbo.uspGetBillOfMaterials'))



INFORMATION_SCHEMA.ROUTINES
This is the problematic one, if the ROUTINE_DEFINITION is greater than 4000 characters then it will be truncated

SELECT ROUTINE_DEFINITION
FROM INFORMATION_SCHEMA.ROUTINES
WHERE SPECIFIC_NAME ='uspGetBillOfMaterials'
AND SPECIFIC_SCHEMA= 'dbo'

Tuesday, June 20, 2006

5 Reasons I Will Blog A Little Less The Next 6 Weeks

Because of these 5 reasons
A) I just moved into a new house and I still have a lot of things to do
B) My wife is 33 weeks pregnant with twins and I have to help her a lot, we also have a son who is 2 (sometimes he acts as if he is in his terrible two’s but mostly not)
C) I still have a lot of things to do to prepare for the babies (mostly buying stuff)
D) I also have a ‘real’ job and we are launching some new products soon
E) It’s the FIFA 2006 World Cup (soccer), I have 2 passports (Dutch and Croatian, but I live in the US) so I have to watch at least all the games when one of my countries is playing

I will be posting a little less of my own content but I will link to other great posts
So today I would like to point out to you a great series of posts about query plans and query executions. I found this blog (http://blogs.msdn.com/craigfr/) after reading Louis Davidson’s blog (http://drsql.spaces.msn.com/)

Here are the posts and they are in FIFO order
The Building Blocks of Query Execution
Viewing Query Plans
Properties of Iterators

Monday, June 19, 2006

Use OBJECTPROPERTY To Generate A List Of Object Types

How do you query the sysobjects system table and get the object type back for every single object
You can use the type and xtype columns, these contain the following data

xtype
Object type. Can be one of these object types:
C = CHECK constraint
D = Default or DEFAULT constraint
F = FOREIGN KEY constraint
L = Log
FN = Scalar function
IF = Inlined table-function
P = Stored procedure
PK = PRIMARY KEY constraint (type is K)
RF = Replication filter stored procedure
S = System table
TF = Table function
TR = Trigger
U = User table
UQ = UNIQUE constraint (type is K)
V = View
X = Extended stored procedure


type
Object type. Can be one of these values:
C = CHECK constraint
D = Default or DEFAULT constraint
F = FOREIGN KEY constraint
FN = Scalar function
IF = Inlined table-function
K = PRIMARY KEY or UNIQUE constraint
L = Log
P = Stored procedure
R = Rule
RF = Replication filter stored procedure
S = System table
TF = Table function
TR = Trigger
U = User table
V = View
X = Extended stored procedure

Or you can use OBJECTPROPERTY. OBJECTPROPERTY is better in my opinion because you can see right away what you are looking for
For example OBJECTPROPERTY ( id , 'IsUserTable' ) is much easier to understand than type = 'u'

Bu using CASE with OBJECTPROPERTY we can generate a nice report

SELECT name,CASE
WHEN OBJECTPROPERTY ( id , 'IsSystemTable' ) =1 THEN 'System Table'
WHEN OBJECTPROPERTY ( id , 'IsProcedure' ) =1 THEN 'Procedure'
WHEN OBJECTPROPERTY ( id , 'IsPrimaryKey' ) =1 THEN 'Primary Key'
WHEN OBJECTPROPERTY ( id , 'IsDefault' ) =1 THEN 'Default'
WHEN OBJECTPROPERTY ( id , 'IsForeignKey' ) =1 THEN 'Foreign Key'
WHEN OBJECTPROPERTY ( id , 'IsCheckCnst' ) =1 THEN 'Check Constraint'
WHEN OBJECTPROPERTY ( id , 'IsView' ) =1 THEN 'View'
WHEN OBJECTPROPERTY ( id , 'IsConstraint' ) =1 THEN 'Constraint'
WHEN OBJECTPROPERTY ( id , 'IsTrigger' ) =1 THEN 'Trigger'
WHEN OBJECTPROPERTY ( id , 'IsScalarFunction' ) =1 THEN 'Scalar Function'
WHEN OBJECTPROPERTY ( id , 'IsTableFunction' ) =1 THEN 'Table Valued Function'
WHEN OBJECTPROPERTY ( id , 'IsRule' ) =1 THEN 'Rule'
WHEN OBJECTPROPERTY ( id , 'IsExtendedProc' ) =1 THEN 'Extended Stored Procedure'
WHEN OBJECTPROPERTY ( id , 'IsUserTable' ) =1 THEN 'User Table'
END ObjectType, *
FROM sysobjects

And of course there are a bunch of INFORMATION_SCHEMA views that you can use to get some of the same information back

SELECT * FROM INFORMATION_SCHEMA.CHECK_CONSTRAINTS
SELECT * FROM INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE
SELECT * FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS
SELECT * FROM INFORMATION_SCHEMA.TABLES
SELECT * FROM INFORMATION_SCHEMA.VIEWS
SELECT * FROM INFORMATION_SCHEMA.COLUMNS

Scriptio 0.5.5 Released

Bill Graziano has released the latest version of his Scriptio tool. What is scriptio?

From Bill's site: "After working with SQL Server 2005 I've discovered that I can't script out one object per file and include both the DROP and CREATE in the same file. Which is driving me absolutely crazy! So I wrote a little utility and thought I'd share it."

You can get the lates version here

Tuesday, June 13, 2006

Check For Valid SMALLDATETIME

Sometime you get data from different sources and the dates are stored in a varchar columnYou need to store that data in your database. The column has a smalldatetime data typeHow do you make sure that the data is correct? You have to use ISDATE and also check that the dates are between 1/1/1900 and 6/6/2079
Here is some code to test that out

CREATE TABLE TestDates(VarCharDate VARCHAR(30))


-- Good smalldatetime
INSERT TestDates
VALUES ('19000101')

--Bad smalldatetime, less than 19000101
INSERT TestDates
VALUES ('18990101')

--Bad smalldatetime, greater than 20790606
INSERT TestDates
VALUES ('20790607')

-- Good smalldatetime
INSERT TestDates
VALUES ('20790606')


--Bad date
INSERT TestDates
VALUES ('abababa')

--This will Fail
SELECT CASE
WHEN ISDATE(VarCharDate) =1 THEN
CONVERT(SMALLDATETIME,VarCharDate)
ELSE
NULL
END
FROM
TestDates

--This will run fine

SELECT VarCharDate,
CASE
WHEN ISDATE(VarCharDate) =1
THEN CASE WHEN VarCharDate BETWEEN '19000101' AND '20790606'
THEN CONVERT(SMALLDATETIME,VarCharDate)
ELSE NULL
END
END
FROM
TestDates


Flo has left a comment, he/she has suggested to convert to datetime in the second case in the case that the date is not stored in the YYYYMMDD format
Here is the suggestion

DECLARE @VarCharDate VARCHAR(100)
SET @VarCharDate = '12/30/2070'

-- Modification:
-- Use CONVERT(DATETIME, @VarCharDate) to check the varchar in any possible format

SELECT @VarCharDate,
CASE
WHEN ISDATE(@VarCharDate) =1
THEN CASE WHEN CONVERT(DATETIME,@VarCharDate) BETWEEN '19000101' AND '20790606'
THEN CONVERT(SMALLDATETIME,@VarCharDate)
ELSE NULL
END
END











Monday, June 12, 2006

COALESCE And ISNULL Differences

I decided to do a quick post about two differences between COALESCE and ISNULL

Run the following block 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)

[Edit] Roji. P. Thomas has an excellent article with even more detailed examples. The links is below.
http://toponewithties.blogspot.com/2004/08/differences-between-coalesce-and.html
[/Edit]

Friday, June 09, 2006

SQl Server Podcast With Gert Drapers (Data Dude)

SQL Down Under has announced their latest podcast with guest Gert Drapers
SQL Server podcast show 17 with Microsoft Architect and Development Manager Gert Drapers. In this show, Gert discusses the upcoming Visual Studio Team Edition for Database Professionals (formally known as Data-Dude).

Get the podcast from SQL Down Under

Retrieve Column Info Of Table Valued Functions By Using INFORMATION_SCHEMA.ROUTINE_COLUMNS

How do you retrieve the columns of Table Valued Functions?
This question was posted to day in the microsoft.public.sqlserver.programming
forum. Although I answered the question I must admit that I have never used the INFORMATION_SCHEMA.ROUTINE_COLUMNS before

So let's see how it works
First create a User-Defined Functions that returns a table data type


USE pubs
GO



CREATE FUNCTION LargeOrder ( @FreightParm
style="color:#3333ff;">money
)
RETURNS @OrderShipperTab TABLE
(
OrderPrice MONEY,
OrderDate DATETIME
)
AS
BEGIN
INSERT
@OrderShipperTab
SELECT OrderPrice, OrderDate
FROM Orders
WHERE OrderPrice > @FreightParm
RETURN
END


--Let's test the function
-- This will return all orders with an order price greater than $40

SELECT *
FROM LargeOrder( 40 )


--Now let's get the column information

SELECT TABLE_NAME,COLUMN_NAME,DATA_TYPE,ORDINAL_POSITION
FROM INFORMATION_SCHEMA.ROUTINE_COLUMNS
WHERE TABLE_NAME ='LargeOrder'
ORDER BY ORDINAL_POSITION

Rename A column In A Table With sp_rename

How do you rename a column in a SQL Server table without using Enterprise Manager/SSMS of course, T_SQL only.
This is a frequent question in the newsgroups and it's causing some confusion for people because you would assume that

you would use the ALTER TABLE syntax, instead of that you have to use sp_rename to rename the column

--Create the table
CREATE TABLE TestRename (id INT,[Some[[Col] INT)

--Do a select to check the column name
SELECT * FROM TestRename

-- This is how you change the dataype
ALTER TABLE TestRename
ALTER COLUMN [Some[[Col] VARCHAR(50)

--this is how you rename the column
EXEC sp_rename 'TestRename.[Some[[Col]', 'SomeCol', 'COLUMN'

--Let’s check again, you will see that the column name has changed
SELECT * FROM TestRename

After changing the column name with sp_rename you will get the following warning
Caution: Changing any part of an object name could break scripts and stored procedures.
The COLUMN was renamed to 'SomeCol'.

Data Dude

Last week I told you about Visual Studio Team Edition for Database Professionals (Data Dude)
Kimberly L. Tripp has a post on her blog with 17 links to websites and 5 links to blogs

Here are the Data Dude team blogs:
Gert Drapers' Blog
Cameron Skinner's Blog
Richard Waymire's Blog
Thomas Murphy's Blog
Database Professional's Team Blog

Vist Kimberly's blog for the whole post

Thursday, June 08, 2006

INFORMATION_SCHEMA.SCHEMATA SQL Server 2005 Change

Everyone keeps saying;” Don’t use the system tables directly but use the ANSI views instead”
So instead of sysobjects use INFORMATION_SCHEMA.TABLES. In SQL Server 2000 instead of using the sysdatabases system table I always used the INFORMATION_SCHEMA.SCHEMATA view to query for the databases. It turns out that that view was no really ANSI compliant to begin with (since SQL server 200 didn’t have schemas of course)
If you run the following query in SQL Server 2000
SELECT CATALOG_NAME, SCHEMA_OWNER
FROM INFORMATION_SCHEMA.SCHEMATA

You will get a result like this




CATALOG_NAME, SCHEMA_OWNER

-------------------------
master..............dbo
tempdb..............dbo
model...............dbo
msdb................dbo
pubs................dbo
Northwind...........dbo




If you run the query in SQL Server 2005 the CATALOG_NAME
will be the same
for every row (it will be the current database name)

However if you run
SELECT SCHEMA _NAME, SCHEMA_OWNER
FROM INFORMATION_SCHEMA.SCHEMATA

You will get the following result set



SCHEMA _NAME, SCHEMA_OWNER
--------------------------------------
dbo.................dbo
guest...............guest
INFORMATION_SCHEMA..INFORMATION_SCHEMA
sys.................sys
HumanResources......dbo
Person..............dbo
Production..........dbo
Purchasing..........dbo
Sales...............dbo
SalesData...........dbo
db_owner............db_owner
db_accessadmin......db_accessadmin
db_securityadmin....db_securityadmin
db_ddladmin.........db_ddladmin
db_backupoperator...db_backupoperator
db_datareader.......db_datareader
db_datawriter.......db_datawriter
db_denydatareader...db_denydatareader
db_denydatawriter...db_denydatawriter




What can you do to query the database name?
Well you can do this

SELECT name FROM master.sys.databases ORDER BY name

Or

SELECT name FROM master..sysdatabases ORDER BY name

According to books on line:
In earlier versions of SQL Server, the INFORMATION_SCHEMA.SCHEMATA view returned all databases in an instance of SQL Server. In SQL Server 2005, the view returns all schemas in a database. This behavior complies with the SQL Standard. For more information, see SCHEMATA (Transact-SQL).

Thursday, June 01, 2006

Use DATEADD And DATEDIFF To Get The Start And End Date For A Quarter

In the microsoft.public.sqlserver.programming forum a person asked how to get the first day of the current quarter. My answer was this: SELECT DATEADD(qq, DATEDIFF(qq, 0, GETDATE())+0, 0)
So I decided to expand on that here

--Start date of the current quarter
SELECT DATEADD(qq, DATEDIFF(qq, 0, GETDATE())+0, 0)

--start and end dates of the current quarter
SELECT DATEADD(qq, DATEDIFF(qq, 0, GETDATE())+0, 0) AS FirstDayOfQuarter,
DATEADD(qq, DATEDIFF(qq, 0, GETDATE())+1, -1) AS LastDayOfQuarter


--start day of the quarter for 20060501
SELECT DATEADD(qq, DATEDIFF(qq, 0, '20060501')+0, 0)

--start and end dates of the quarter for 20060501
SELECT DATEADD(qq, DATEDIFF(qq, 0, '20060501')+0, 0) AS FirstDayOfQuarter,
DATEADD(qq, DATEDIFF(qq, 0, '20060501')+1, -1) AS LastDayOfQuarter


--start and end dates of the quarter for 20060201
SELECT DATEADD(qq, DATEDIFF(qq, 0, '20060201')+0, 0) AS FirstDayOfQuarter,
DATEADD(qq, DATEDIFF(qq, 0, '20060201')+1, -1) AS LastDayOfQuarter

Top 5 Posts For May 2006

Below are the top 5 posts according to Google Analytics for the month of May

Login failed for user 'sa'. Reason: Not associated with a trusted SQL Server connection. SQL 2005
OPENROWSET And Excel Problems
Fun With SQL Server Update Triggers
SQL Query Optimizations
Split a comma delimited string fast!


Top SQL Server Google Searches For May 2006

These are the top SQL Searches on this site for the month of May. I have left out searches that have nothing to do with SQL Server or programming. Here are the results...

microsoft access
charindex city state zip
point into polygon
enterprise manager
cast example - sql
alter identity increment
Syntax Error Converting The Varchar Value To A Column Of Data Type Int hibernate
server updates varchar column to null
lock select
distinct
exists
password case sensitive site:sqlservercode.blogspot.com
insert
dynamic scroll