How MySQL confirms that the Update,delete,insert statement executed successfully

How does MySQL confirm that the Update,delete,insert statement was executed successfully?
Title, now through Mysql_affected_rows () in judgment, so that the words will cause almost every sentence update,delete,insert behind must follow a sentence
if (Mysql_affected_rows ()!=1)
{
Error
}

Is there any more convenient way?
------to solve the idea----------------------
If you don't trust update ... set money=money-1 will actually execute
Do you need to select again to confirm that money is reduced by 1 instead of 100?

$result = mysql_query ("Update ...")
False is returned only if the SQL instruction is an error
So there's no need to try

