查询加入同一个表3次

Question

I have created a query that works perfectly in phpMyAdmin, however when I try to call it in a .php file I get the following error.

Undefined variable: mothers_name in C:\wamp\www\Family_Tree\showfamily.php on line 56

My code is:

$select_query = "SELECT a.id, CONCAT( a.surname,  ', ', a.first_names ) AS child_name, " . 
"CONCAT( b.surname,  ', ', b.first_names ) AS mothers_name, " .
"CONCAT( c.surname, ', ', c.first_names ) AS fathers_name " .
"FROM family_members a " .
"INNER JOIN family_members b ON a.mother_id = b.id " .
"INNER JOIN family_members c ON a.father_id = c.id" .
"WHERE a.id = " . $user_id;

Am I getting this error because the tables "a","b" and "c" and the fields "mother_id" and "father_id" doesn't exist until the SQL is called through the mysql_query($select_query) function.

The code before line 56 looks up, returns and displays the results as they should.

Answer 1

..._id = c.id" .               // <-- you forgot a space, results in c.idWHERE
"WHERE a.id = " . $user_id;