printeero when It can not connect to database

how can I put code to  check error when connect to my sql database of this code below

header('Content-Type: text/html; charset=utf-8');
include "./";
$register_script = "./register.php";

function auth_user($userid, $userpassword) {
   global $default_dbname1, $user_tablename;
   $link_id = db_connect1($default_dbname1);
   $query = "SELECT nickname FROM $user_tablename
                             WHERE nickname = '$userid'
                             AND password = '$userpassword' AND stockad = 'y' ";
   $result = mysql_query($query);
   if(!mysql_num_rows($result)) return 0;
   else {
      $query_data = mysql_fetch_row($result);
      return $query_data[0];
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Loganathan NatarajanLAMP DeveloperCommented:
you need to work around in this function , db_connect1() ...

also in your query, you should handle like this,

   $result = mysql_query($query) or die(mysql_error("error occured"));

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MySQL Server

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