Question

I have a DB (user_interests) set up with 3 fields: i_id (unique), interest_id, uid.

Then a second DB (interests) set up with the interests: interest_id (unique), interest_name

I’d like to do an SQL query to return a list of interests that two users have in common: User A (owner of a profile) and user B (you/viewer of a profile). I guess I need to query user_interests, then JOIN interests to get the name of the interest.

SELECT user_interests.i_id, user_interests.uid, interests.interest_name 
FROM databases.user_interests 
LEFT JOIN databases.interests 
ON interest.interest_id = user_interest.interest_id 
WHERE _______________

I’m confused about the where clause (if that is the correct way to do it at all). My goal is to get the interest_id from user_interests.interests where user_interests.uid is both A and then B (in separate rows).

I saw this link, but couldn’t figure out what exactly I was missing: Group by x where y = A and B and C

Answer 1

I don’t think you need the where clause in this case just remove it and you will get the set of data you are looking for:

SELECT user_interests.i_id, user_interests.uid, interests.interest_name 
FROM databases.user_interests 
LEFT JOIN databases.interests 
ON interest.interest_id = user_interest.interest_id