Question

I have two tables:

Contact (id,name)
Link (id, contact_id, source_id)

I have the following query which works that returns the contacts with the source_id of 8 in the Link table.

SELECT name FROM `Contact` LEFT JOIN Link ON Link.contact_id = Contact.id WHERE Link.source_id=8;

However I am a little stumped on how to return a list of all the contacts which are NOT associated with source_id of 8. A simple != will not work as contacts without any links are not returned.

Thanks.

Answer 1

Use:

   SELECT c.name 
     FROM CONTACT c
LEFT JOIN LINK l ON l.contact_id = c.id
                AND l.source_id = 8
    WHERE l.contact_id IS NULL