Question

Basically a live feed of all your friends’ recent posts.

In a stupid sort of approach I think I’d start by building a query like:

SELECT * FROM tblposts WHERE userid=friend_id_1OR userid=friend_id_2...... and so on

Where friend_id_% is the userid of a friend from your friends list. But this must be a very inefficient way of doing it, right? Is there any faster way of doing this in MySQL? Maybe some clever DB schema?

(I know FB uses Hadoob but I’m not experienced enough to go that far 🙁 )

Answer 1

If you have a list of IDs that you want to query then you should use IN:

SELECT * FROM tblposts WHERE userid IN (friend_id_1, friend_id_2, ...)

But in this case I think you can use a join instead.

SELECT * FROM tblposts AS T1
JOIN (
   SELECT friendid             -- I just made up this query.
   FROM friends                -- You need to replace it with the
   WHERE userid = 'youruserid' -- real query to get someone's friends.
) AS T2
ON T1.userid = T2.friendid