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

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