SQL Server - transactions roll back on error?

Question

We have client app that is running some SQL on a SQL Server 2005 such as the following:

BEGIN TRAN;
INSERT INTO myTable (myColumns ...) VALUES (myValues ...);
INSERT INTO myTable (myColumns ...) VALUES (myValues ...);
INSERT INTO myTable (myColumns ...) VALUES (myValues ...);
COMMIT TRAN;

It is sent by one long string command.

If one of the inserts fail, or any part of the command fails, does SQL Server roll back the transaction? If it does not rollback, do I have to send a second command to roll it back?

I can give specifics about the api and language I'm using, but I would think SQL Server should respond the same for any language.

Answer 1

If one of the inserts fail, or any part of the command fails, does SQL server roll back the transaction?

No, it does not.

If it does not rollback, do I have to send a second command to roll it back?

Sure, you should issue ROLLBACK instead of COMMIT.

If you want to decide whether to commit or rollback the transaction, you should remove the COMMIT sentence out of the statement, check the results of the inserts and then issue either COMMIT or ROLLBACK depending on the results of the check.

Answer 2

You are correct in that the entire transaction will be rolled back. You should issue the command to roll it back.

You can wrap this in a TRY CATCH block as follows

BEGIN TRY
    BEGIN TRANSACTION

        INSERT INTO myTable (myColumns ...) VALUES (myValues ...);
        INSERT INTO myTable (myColumns ...) VALUES (myValues ...);
        INSERT INTO myTable (myColumns ...) VALUES (myValues ...);

    COMMIT TRAN -- Transaction Success!
END TRY
BEGIN CATCH
    IF @@TRANCOUNT > 0
        ROLLBACK TRAN --RollBack in case of Error

    -- you can Raise ERROR with RAISEERROR() Statement including the details of the exception
    RAISERROR(ERROR_MESSAGE(), ERROR_SEVERITY(), 1)
END CATCH

Answer 3

You can put "set xact_abort on" before your transaction to make sure sql rolls back automatically in case of error.