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Controlling SQL Transactions with SQL Server 2000 and ADO.NET

Posted on 2011-09-16
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Last Modified: 2012-05-12
Hi

I have to work on a system that has a SQL Server 2000 database. I am using C# and ADO.NET to access the database. I now have an update to do with 4 tables. Now with SQL Server 2008 I can use a try.. catch block and rollback any failed updates. But given the technology I'm using can someone suggest the most sensible way to begin/rollback/commit a transaction with SQL Server 2000 ?

Many thanks..
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Question by:jonatec
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Accepted Solution

by:
chandrasekar1 earned 400 total points
ID: 36548199
we can catch the error through @@ERROR, while exceuting queries, if there was any error, @@ERROR will set not equal to “0”
below I given 2 approaches using with GOTO and without GOTO.  

Approach 1:

BEGIN TRAN
    UPDATE Authors
    SET Phone = '415 354-9866'
    WHERE au_id = '724-80-9391'

    IF (@@ERROR <> 0) GOTO PROBLEM

    UPDATE Publishers
    SET city = 'Calcutta', country = 'India'
    WHERE pub_id = '9999'

    IF (@@ERROR <> 0) GOTO PROBLEM
COMMIT TRAN

PROBLEM:
IF (@@ERROR <> 0) BEGIN
PRINT 'Unexpected error occurred!'
    ROLLBACK TRAN
END

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In above approach, we need to write “GOTO” statement after each DML operation, if any error occurs, then it will Rollback the transaction.

Approach 2:

BEGIN TRAN
    UPDATE Authors
    SET Phone = '415 354-9866'
    WHERE au_id = '724-80-9391'

    UPDATE Publishers
    SET city = 'Calcutta', country = 'India'
    WHERE pub_id = '9999'

IF (@@ERROR = 0) 
BEGIN
COMMIT TRAN
END
ELSE
BEGIN
IF (@@ERROR <> 0) BEGIN
PRINT 'Unexpected error occurred!'
    ROLLBACK TRAN
END

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Author Comment

by:jonatec
ID: 36548313
Thanks for that.

Question I have is; will SQL Server 2000 control an error caused when a table or column has been accidentally renamed or a column deleted, or will it just crash out ?
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Expert Comment

by:jogos
ID: 36548480
It will give a severe error, not controlable just stops , rollback and gives error like 'unkown ...'  
From SQL2005 you have more control.  But 'accidentally' renamed or deleted column is something
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LVL 3

Expert Comment

by:chandrasekar1
ID: 36548555
it will crash, if you want to avoid this situation, before doing the DML operation, you can check in the “information_schema.columns” view and then you can proceed it.
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LVL 25

Expert Comment

by:jogos
ID: 36548664
The sql will crash, but the error returned is perfectly capturable in your C#-code to let it there have an elegant exit.
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Author Comment

by:jonatec
ID: 36548738
Is it better to escalate the problem back to ADO.NET and create a rollback there ?
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Assisted Solution

by:hspoulsen
hspoulsen earned 100 total points
ID: 36549159
You should take a look at www.sommarskog.se, in particular http://www.sommarskog.se/error-handling-II.html
that describes what to do on SQL Server 2000.

The solution by chandrasekar1 is fine, but you will not be able to see the @@error number, because "After each statement, SQL Server sets @@error to 0 if the statement was successful" (quote from link above)

Best regards,
Henrik Staun Poulsen
Stovi Software
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Author Closing Comment

by:jonatec
ID: 36549199
Thanks. Very useful.
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Expert Comment

by:hspoulsen
ID: 36549292
you should not use Approach 2, as

SQL Server sets @@error to 0 if the statement was successful

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Author Comment

by:jonatec
ID: 36549366
Agreed. I'll use approach 1.
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