Question

Tables:

• users: id, name
• usersFacebookFriends: id, uid, friendUid, name

I need a query to search for friends (name), and check if they exists in the users table, so then they are also on the website registered.

Is this possible with a left join, and if so how?

Thanks.

Answer 1

I guess this should make a job. If facebook friend is not registered with your site corrsponding joined User table fields will be NULL.

SELECT f.name, u.* FROM usersFacebookFriends AS f
LEFT JOIN users AS u
ON f.friendUid = u.id
WHERE f.uid = 123

Change LEFT JOIN to INNER JOIN if you need to find only those who exist.