Потеря соединения с БД

 $connect_server = mysql_connect("localhost","root","") or die("No connection");
 $select_db = mysql_select_db('CAS',$connect_server) or die("No db");
 $sql = "SELECT piece FROM tbl WHERE square=\"$id1\"";
 $result = mysql_query($sql) or die("Can't select");
 $res = mysql_fetch_array($result);
 if($res[0] != '')
 {
     $sql = "UPDATE tbl SET piece=\"$res[0]\" WHERE square=\"$id2\"";
     $result = mysql_query($sql) or die("Can't update 1");
     $sql = "UPDATE tbl SET piece='' WHERE square=\"$id1\"";
     $result = mysql_query($sql) or die("Can't update 2");
 }
 mysql_close($connect_server);

<?php // connection.php
  $connect_server = mysql_connect("localhost","root","") or die("No connection");
  $select_db = mysql_select_db('CAS',$connect_server) or die("No db");
?>

require_once("connection.php");
 
function movePiece($idFrom,$idTo)
{
// $connect_server = mysql_connect("localhost","root","") or die("No connection");
// $select_db = mysql_select_db('CAS',$connect_server) or die("No db");
... тело запроса...
}
 
function showPiece($id)
{
// $connect_server = mysql_connect("localhost","root","") or die("No connection");
// $select_db = mysql_select_db('CAS',$connect_server) or die("No db");
... тело запроса...
}