mysql - INNER JOIN same table

Question

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 row and user_parent_id row. I have coded something like this:

SELECT user.user_fname, user.user_lname
FROM users as user
INNER JOIN users AS parent
ON parent.user_parent_id = user.user_id
WHERE user.user_id = $_GET[id]

But it doesn't show the results. I want to display user record and its parent record.

Answer 1

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.