SQL Join Statement to collect both user's friends' and user's messages
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I have 3 Tables: Messages, Users, and Friends. 
Messages: msg_id, uid_fk, message, alert, created, uploads, owner
Users: uid, first_name, last_name
Friends: friend_one, friend_one

When a user becomes friends with another user, I record their uid's in the following manner: friend_one:172  friend_two:58 | friend_one: 58 friend_two: 172
My code below works perfectly and goes through to select all of the user's message updates. My problem is that I need to select all of the messages of not only the user himself/herself but also all of his or her friends messages too. 

The following below as mentioned above selects only the user's status updates and I have been struggling for hours to select not only the user's status updates but also his or her friends with it. 

    $query = $db->prepare("SELECT M.msg_id, M.uid_fk, M.message, M.alert, 
    M.created, M.uploads , M.owner , U.uid , U.first_name , U.last_name FROM 
    messages M, users U  WHERE M.uid_fk=U.uid and M.uid_fk= :uid_fk limit 10");
    $query->execute(array(':uid_fk' => $uid));

($uid is session id of logged-in user) 

Also my code for selecting friends just in case: 

    $friends_sql = $db->prepare("SELECT a.first_name, a.uid, a.last_name FROM users 
    a, friends b WHERE a.uid = b.friend_two AND b.friend_one = :friend_one ORDER BY 
    b.friend_id DESC LIMIT 8");
    $friends_sql->execute(array(':friend_one' => $uid));