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Wednesday, June 06, 2007

How To Protect Yourself From Fat-Finger Sally, Crazy Bosses and Other SQL Villains

You all have been through this at least once in your life. In your shop there is this one person who likes to use Enterprise Manager as their Rapid Data Entry Application. We all know how these people operate; they delete rows, drop tables and all kinds of other funky stuff. SQL Server 2005 has DDL triggers to help you protect against these scoundrels. What about if you are still running that piece of software from the late Triassic period known as SQL Server 2000, what can help you in that case? Don’t worry I will show you a way but first I will tell you a story. About 6 years ago I worked in New York City as a consultant on a project for a nonprofit organization. I looked in the database and found this table which was named YesNoTable. I was curious I opened the table and noticed it had only 2 rows. Here is what was stored in the table.

0 no
1 yes

I dropped it immediately. 5 minutes went by and suddenly the CRM application was broken. They ran the debugger and found out a table was missing. Luckily for me it was very easy to recreate this table. And yes, we did get rid of it soon after. Now had the table be used by a view which had been created with schemabinding I would not be able to drop the table without dropping the view first. You see even I became a SQL villain one time.

What the code below does is it will loop through all the user created tables then union them all, I created a where 1 =0 WHERE clause just in case someone decides to open the view. Since a union can only have 250 selects or so, I have created the code so that you can specify how many tables per view you would like, you do that with the @UnionCount variable.

The code does print statements it does not create the views

If you run the code in the msdb database and you specify 5 as the @UnionCount your output will be this

-- ****************************
-- **** View Starts Here *****
-- ****************************
CREATE VIEW DoNotDropMe_1 WITH SCHEMABINDING
AS
SELECT 1 As Col1 FROM [dbo].[log_shipping_databases]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[log_shipping_monitor]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[log_shipping_plan_databases]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[log_shipping_plan_history]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[log_shipping_plans]
WHERE 1=0
GO


-- ****************************
-- **** View Starts Here *****
-- ****************************
CREATE VIEW DoNotDropMe_2 WITH SCHEMABINDING
AS
SELECT 1 As Col1 FROM [dbo].[RTblClassDefs]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[RTblDatabaseVersion]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[RTblDBMProps]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[RTblDBXProps]
WHERE 1=0
UNION ALL
SELECT 1 As Col1 FROM [dbo].[RTblDTMProps]
WHERE 1=0
GO


The code is not very complex if there are more tables in the DB than you specify in the @UnionCount variable then it will do them in chunks of whatever you specified, if there are less then it will do all of them in 1 view.
Below is the code, if you have any questions then feel free to leave a comment.

USE msdb
SET NOCOUNT ON

DECLARE @UnionCount int
SELECT @UnionCount = 20

IF @UnionCount > 250 OR @UnionCount <1
BEGIN
RAISERROR ('@UnionCount has to be between 1 and 250', 16, 1)
RETURN
END

SELECT identity(int,1,1) AS id,QUOTENAME(table_schema) + '.' + QUOTENAME(table_name) AS tablename
INTO #Tables
FROM information_schema.tables
WHERE table_type ='base table'
AND OBJECTPROPERTY(OBJECT_ID(table_name),'IsMSShipped') = 0
ORDER BY table_name

DECLARE @maxloop int
DECLARE @loop int
DECLARE @tablename varchar(200)




SELECT @maxloop = MAX(id)
FROM #Tables

BEGIN
DECLARE @OuterLoopCount int, @OuterLoop int

SELECT @OuterLoopCount = COUNT(*) FROM #Tables
WHERE id %@UnionCount =0

SELECT @OuterLoopCount = COALESCE(NULLIF(@OuterLoopCount,0),1)



IF (SELECT COUNT(*) FROM #Tables) % 10 <> 0
SELECT @OuterLoopCount = @OuterLoopCount +1

SELECT @OuterLoop =1

SELECT @Loop = MIN(id),@maxloop=MAX(id)
FROM #Tables WHERE ID <= @UnionCount * @OuterLoop

WHILE @OuterLoop <=@OuterLoopCount
BEGIN
SELECT @Loop = MIN(id),@maxloop=MAX(id)
FROM #Tables WHERE ID <= @UnionCount * @OuterLoop
AND id > (@UnionCount * @OuterLoop) - @UnionCount


PRINT'-- **************************** '
PRINT'-- **** View Starts Here ***** '
PRINT'-- **************************** '
PRINT 'CREATE VIEW DoNotDropMe_' + CONVERT(VARCHAR(10),@OuterLoop) + ' WITH SCHEMABINDING'+ char(10) + 'AS'
WHILE @Loop <= @maxloop
BEGIN
SELECT @tablename = tablename
FROM #Tables
WHERE id = @Loop
PRINT 'SELECT 1 As Col1 FROM ' + @tablename + char(10) + 'WHERE 1=0'
IF @Loop < @maxloop
PRINT UNION ALL'
SET @Loop = @Loop + 1

END
SET @OuterLoop = @OuterLoop + 1
PRINT 'GO'
PRINT ''
PRINT ''

END
END


DROP table #Tables


Cross-posted from SQLBlog! - http://www.sqlblog.com/

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