LEFT OUTER JOIN query not returning expected rows

Question

My aim is to do exactly what a LEFT OUTER JOIN intends to do using the 4th venn diagram: SQL Diagrams:

Answer 1

Use

SELECT * 
   FROM   consultant_memberships 
       LEFT  Outer JOIN consultant_memberships_list 
                ON consultant_memberships_list.membership_id = consultant_memberships.`id`  
                and  consultant_memberships_list.consultant_id = 5 
 where  consultant_memberships_list.membership_id IS NULL;

The Where clause used before in your query "consultant_memberships_list.consultant_id = 5 " was neglecting the left outer join.

Answer 2

You current query is basically doing an INNER JOIN because of the consultant_id = 5 on the WHERE clause. I believe you actually want to use:

SELECT * 
FROM   consultant_memberships m
LEFT OUTER JOIN consultant_memberships_list l
  ON m.`id` = l.membership_id 
  AND l.consultant_id = 5 
WHERE l.membership_id IS NULL;

See SQL Fiddle with Demo