Question

Let’s say I have an SQL statement that’s syntactically and semantically correct so it executes.

In Management Studio (or any other query tool) how can I test SQL statements, and if I notice that they broke something, rollback (in a separate query?)

Answer 1

The easisest thing to do is to wrap your code in a transaction, and then execute each batch of T-SQL code line by line.

For example,

Begin Transaction           -Do some T-SQL queries here.  Rollback transaction -- OR commit transaction 

If you want to incorporate error handling you can do so by using a TRY…CATCH BLOCK. Should an error occur you can then rollback the tranasction within the catch block.

For example:

USE AdventureWorks; GO BEGIN TRANSACTION;  BEGIN TRY     -- Generate a constraint violation error.     DELETE FROM Production.Product     WHERE ProductID = 980; END TRY BEGIN CATCH     SELECT          ERROR_NUMBER() AS ErrorNumber         ,ERROR_SEVERITY() AS ErrorSeverity         ,ERROR_STATE() AS ErrorState         ,ERROR_PROCEDURE() AS ErrorProcedure         ,ERROR_LINE() AS ErrorLine         ,ERROR_MESSAGE() AS ErrorMessage;      IF @@TRANCOUNT > 0         ROLLBACK TRANSACTION; END CATCH;  IF @@TRANCOUNT > 0     COMMIT TRANSACTION; GO 

See the following link for more details.

http://msdn.microsoft.com/en-us/library/ms175976.aspx