function getFriendList($uid) {
  $query = mysql_query("select * from friens where user_id=$uid");
  if ($query) return mysql_fetch_array($query);
  else return "NaN";
}
function addToFriend($uid, $frId) {
  $query = mysql_query("select * from friens where user_id=$uid and friend=$frId");
  if ($query) return "Пользователь уже в списке ваших друзей";
  else {
   $query = mysql_query("INSERT into friends (id, user_id, friend) values (NULL, $uid, $frId)");
   if ($query) return "Done";
   else return "Error";
  }
}

$fr = mysql_query("SELECT * FROM `friends` WHERE `user_id`=".$myrow3[id]."");   
while ($fri = mysql_fetch_array($fr)){    
$frilog = mysql_query("select * from `users` WHERE `id`='$fri[friend]'") or die("MySQL Error!");   
$frilogg = mysql_fetch_array($frilog);
echo "<a href='page.php?id=".$fri[friend]."' target='blank'><img src=/img/other/inf.png ></a>".$frilogg['login']."<br>";   
}

<?php
function listFriends($u_id){
$fr = mysql_query("SELECT * FROM `friends` WHERE `user_id`=".$u_id."");    
while ($fri = mysql_fetch_array($fr)){     
$frilog = mysql_query("select * from `users` WHERE `id`='$fri[friend]'") or die("MySQL Error!");    
$frilogg = mysql_fetch_array($frilog);   
echo "|".$frilogg['login']."|<br>";    
}}
function add_Frind($friend){
if (!empty($_GET['active']) and !empty($_GET['id'])){
$active = $_GET['active'];
$id = $_GET['id'];   
$myrow3 = mysql_fetch_array(mysql_query("SELECT * FROM users WHERE id=$id"));
$uid = $_SESSION['id'];   
$query = mysql_query("select * from friens where user_id=$uid and friend=$friend");   
if($query){echo"Пользователь уже в списке ваших друзей";}else{
$query = mysql_query("INSERT into friends (id, user_id, friend) values (NULL, $uid, $friend)");   
if ($query){echo"Пользователь добавлен";
}else{echo "Error";}}}}

# Пример   
echo listFriends("1"); // показываем список друзей пользователя у которого id=1
?>