如何显示确认的朋友

I have a table named user_join:

| join_to_id | join_by_id | approved |

join_to_id means to whom user sending the request

join_by_id means who is sending request

approved means request accepted or not, if accepted value will be 'Yes' else value will be 'No'

Now I want to display the names of those users who APPROVED BY current id user or who APPROVED CURRENT id user.

Here is my code :

$query = "SELECT * FROM user_join where (join_to_id = '".$_GET['id']."' and approved = 'Yes' and join_by_id != '".$_GET['id']."' ) 
          or (join_by_id = '".$_GET['id']."' and approved = 'Yes' and join_to_id != '".$_GET['id']."') ORDER BY id DESC";

You are thinking much too complicated. This should do it:

 SELECT * 
 FROM user_join 
 WHERE '".$_GET['id']."' IN (join_to_id, join_by_id) 
 AND approved='Yes'

A user is not going to friend himself.

Side note: You should use prepared statements or at least escape the input from $_GET to prevent SQL injections.