check for duplicate entry vs use PDO errorInfo result

Question

I have a MySQL table which has a field for email addresses which is defined as unique. For this example, let\'s say that all my form does is allow a user to insert their em

Answer 1

You could be executing this with a try catch block:

try {
   $prep->execute($values);
   // do other things if successfully inserted
} catch (PDOException $e) {
   if ($e->errorInfo[1] == 1062) {
      // duplicate entry, do something else
   } else {
      // an error other than duplicate entry occurred
   }
}

You could also look into alternatives such as "INSERT IGNORE", and "INSERT... ON DUPLICATE KEY UPDATE" - though I think those are MySQL specific and would go against the portability of using PDO, if that's something you're concerned about.

Edit: To more formally answer your question, to me, solution #1 (the defensive programmer) in full usage effectively eliminates the point of the unique constraint in the first place. So I would agree with your thought of letting MySQL take care of data checking.