this code is check the available user names but it is not working

this code is check the available user names but it is not working

if($login != '') { $query = "SELECT * FROM members WHERE
UserName='$login'"; $result = mysql_query($query); if($result) {
if(mysql_num_rows($result)>0) { $u = 'UserName already in use'; }
@mysql_free_result($result); } else { die("Query failed"); } }