В чём ебучая ошибка*?

PHP:

1. function icon_user($user_id){
2.   /*строка 182*/ $people = mysqli_fetch_assoc(mysqli_query($link, "SELECT * FROM `users` WHERE `id` = '$user_id' LIMIT 1"));
3.  
4.   if($people['online'] > time()-600){
5.     $image = "<img class='icon' src='/icon/".$people['sex'].".png' width='20px'>";
6.   }else{
7.     $image = "<img class='icon' src='/icon/".$people['sex'].".png' style='opacity: 0.3;' width='20px'>";
8.   }
9. return $image;
10. }

Notice: Undefined variable: link in /functions.php on line 182
Warning: mysqli_query() expects parameter 1 to be mysqli, null given in /functions.php on line 182
Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, null given in /functions.php on line 182