SELECT multiple table

i need some help here,

table "friends"
+------+-------------+-----------+
   id  |  friend_id  |   user_id |
+------+-------------+-----------+
   1   |    1222     |   99999   |
+------+-------------+-----------+
   2   |   48989     |   1492    |
+------+-------------+-----------+

table "users"
+------+-------------+---------------+
   id  |  user_name  |   user_image  | 
+------+-------------+---------------+
 99999 |     Mark    | img/abc.jpg   |
+------+-------------+---------------+
 1222  |     Tom     | img/xyz.jpg   |
+------+-------------+---------------+
 etc.  |    etc.     |       etc..   |
+------+-------------+---------------+

i want SELECT table friends and make WHERE statement :

etc : ... WHERE user_id=$_SESSION[u开发者_Python百科ser_id] ... and will display data from table users

ok , let say : my current id is 99999 so in table friends is match only 1222 , so this will display all data(image,etc..) from id 1222(Tom) from table users.

So my question here is how i need to write this code for generate users data ?

*i try to use UNION and LEFT JOIN..but no luck..still newbie..

---

$user_id = intval($_SESSION['user_id']);
$friends_of_user = mysql_query('
SELECT 
   f.*, u.* 
FROM  
    friends f 
  LEFT JOIN 
      users u 
  ON 
      u.id = f.friend_id
WHERE 
      f.user_id = '.$user_id);

and to exclude all users which doesn't have profiles in users table, just change LEFT JOIN to JOIN

---

I'd use the following code:

$user_id = mysql_real_escape_string($_SESSION['user_id']);
$sql = "SELECT f.* 
        FROM users u
        INNER JOIN friends f ON (u.user_id = f.friend_id)
        WHERE u.user_id = '$user_id' ";