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

The solution is to select each column explicitly everywhere. Don't use user.* and user_info.* in your select list, either:

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