Daily Archives: 2013/10/15

Line numbers in t-sql error messages

When you run scripts in SSMS and get an error, the error references a line number in the t-sql statement that caused the error. If you double click the error, SSMS will take you to the error. This works even if you have multiple statements in your query window. So it can be a really helpful feature. But if the error is in code that isn’t in the query window (for instance in a referenced stored procedure), nothing happens when you double click. In that case it can be good to know how SSMS calculates the line number in error messages.

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Create or Replace

Blog series: SQL Server Connect Items

How many times have you been forced to change a “CREATE” statement to “ALTER” because “There is already an object…”:

Msg 2714, Level 16, State 3, Procedure XXX, Line 1 There is already an object named XXX in the database.
Msg 2714, Level 16, State 3, Procedure XXX, Line 1 There is already an object named XXX in the database.

And then you need to change it back to “CREATE” in the script, or else it won’t work when deploying. This will happen if you try to issue a “ALTER” statement on a object that does not exist:

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Rowlock can block more than a row

To avoid the blocking of other users, rowlocks are sometimes used to create locks on the most granular locking level in a table. In theory, when user A makes changes to a row, user B can read, change or delete any other row than that. But in practice, user B can still become blocked by user A altough they are not accessing the same row. It all depends on how data is accessed.

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Missing comma between columns in select statement

Hopefully, when you make an typing error while writing a SQL statement, you get the red curly lines under the offending part of the query showing you where the error is. If you execute the following statement, you’ll get an error message:

Msg 102, Level 15, State 1, Line 1 Incorrect syntax near 'FROMTABLE'.
Msg 102, Level 15, State 1, Line 1 Incorrect syntax near ‘FROMTABLE’.

However, some typos doesn’t create an syntax error. Instead it alters the meaning of the t-sql statement in an perhaps unwanted way. Check out the following example.

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Zero footprint Server/Database DDL Trigger

Aaron Bertrand has written a great introduction to server/database DDL triggers in his article SQL Server DDL Triggers to Track All Database Changes.

I wanted to implement similar DDL triggers on more or less all servers. Some of the databases on those servers were from a 3:rd party, so changes in those databases wasn’t possible. Therefore I wanted to make sure these DDL triggers were “zero footprint”. That is, not causing existing database code to fail. I simply added TRY and an empty CATCH to the trigger, believing I’d be safe. Unfortunately, an error like this…

Msg 3616, Level 16, State 2, Procedure SP1, Line 5 An error was raised during trigger execution. The batch has been aborted and the user transaction, if any, has been rolled back.
Msg 3616, Level 16, State 2, Procedure SP1, Line 5 An error was raised during trigger execution. The batch has been aborted and the user transaction, if any, has been rolled back.

…happened to a SQL Agent job running during the evening.

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