MySQL 'user_id' in where clause is ambiguous problem

Question

How can I correct the problem I keep getting from the code below which states \'user_id\' in where clause is ambiguous. Thanks for the help in advance.

Answer 1

Try this.

SELECT u.user_id, u.user_fudge, ui.foo, ui.bar
FROM user AS u
INNER JOIN user_info AS ui
   ON ui.user_id = u.user_id
WHERE u.user_id = '$user_id';