php - Is it necessary to write ROLLBACK if queries fail?

Question

I write

mysql_query("SET AUTOCOMMIT=0");
mysql_query("START TRANSACTION");

before I write all queries. Then check if all of them are true and then write:

mysql_query("COMMIT");

But if one of query fails, I just pass COMMIT query. So do I really need ROLLBACK function if one of the queries fail? Because without ROLLBACK it also works.
Thanks.

Answer 1

I think you're asking if executing ROLLBACK is necessary, since without it the commits still don't get applied. That's technically true, but only because the transaction is still open since you haven't ended it. Anything that implicitly commits the transaction (for example, starting a new transaction) will act as though you ran COMMIT, which is the opposite of what you want