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?)
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
Hope this helps but please let me know if you need more details.