Question

$query = "INSERT IGNORE INTO `user` (`name`, `email`) VALUES ( '".$name."', '".$email."')";
$res = mysql_query($query) or die("Query failed ".mysql_error() );
$last id = mysql_insert_id();

mysql_insert_id() return 0 if there is a duplicated entry.

Is there a way to get the ID of the duplicated entry ? or do I have to do 2 query ( SELECT + INSERT ) ?

Answer 1

There is no way with an INSERT to get the ID of the existing (duplicate) entry.

Still, you should not do a SELECT + INSERT because you would need to lock the table for concurrency (to ensure that nothing has changed between SELECT and INSERT).

In this case, if the insert fails, and you want to update the existing record instead, use INSERT … ON DUPLICATE KEY UPDATE.

If you just want to fail, but have the existing ID, then fail, and do a SELECT to get the existing entry.