SQL join help for friend list

Question

I have three database tables: users, user_profiles and friends:

users

• id
• username

Answer 1

This may not be the best way to do it, but this felt like the logical way:

select a.id , a.friend_id ,
Users.username
from
 ( SELECT id , IF(usera_id = 1, userb_id , usera_id) friend_id
 FROM friends
 where usera_id = 1 OR userb_id = 1 ) a
left join Users on a.friend_id = Users.id

this uses a mySQL function so probably wont work in Oracle/MSSQL