This query will get you the last record inserted before you ran this query.
Don't use this if you want to get information about a record that you have just inserted.
Why not?
Because a database can run several queries at the same time.
That means that other script/people can insert records while you are preparing to run this query.
If they do, you will see their records instead of yours.
Instead, use mysql_insert_id() to get the auto_increment column value for the last record inserted using your database-connection.