$sql = "select u.Id, u.username, u.email, (NOW()-u.authenticationTime) as authenticateTimeDifference, u.IP,
f.providerId, f.requestId, f.status, u.port
from friends f
left join users u on
u.Id = if ( f.providerId = ".$userId.", f.requestId, f.providerId )
where (f.providerId = ".$userId." and f.status=".USER_APPROVED.") or
f.requestId = ".$userId." ORDER BY u.username ASC";
I don´t understand the if meaning here , being used with where
// providerId and requestId is Id of a friend pair,
// providerId is the Id of making first friend request
// requestId is the Id of the friend approved the friend request made by providerId
// fetching friends,
// left join expression is a bit different,
// it is required to fetch the friend, not the users itself