I am trying to get some rows from the same table. It\'s a user table: user has user_id and user_parent_id.
I need to get the user_id
I think the problem is in your JOIN condition.
SELECT user.user_fname,
user.user_lname,
parent.user_fname,
parent.user_lname
FROM users AS user
JOIN users AS parent
ON parent.user_id = user.user_parent_id
WHERE user.user_id = $_GET[id]
Edit:
You should probably use LEFT JOIN if there are users with no parents.