PHP-mysql数据库并没有以并行方式更新

朋友们好，

我有一个mysql数据库和一个php页面。当我或有人调用我的php页面时，它正在顺利地更新我的表。

但当它同时被多个用户调用时，它并没有正确地更新表。它只更新一个用户的进程。我正在使用standart mysql连接。我尝试过ADO数据库连接，但问题并没有解决。问题出在哪里？

这是我的php页面；

<?php

        $host  ="******.com";
        $uname = "*****";
        $pwd = "*******";
        $db = "*****_db";

    $con = mysql_connect($host,$uname,$pwd) or die("connection failed");
    mysql_select_db($db,$con) or die("db selection failed");
        $id = $_REQUEST['id'];
        $int_id = intval($id);
        $value = 0;
           if (isset($_REQUEST['vote1']))
            {
               $vote1 = $_REQUEST['vote1'];
               $value = 1;
               $vote = intval($vote1);
             }
             if (isset($_REQUEST['vote2']))
            {
                $vote2 = $_REQUEST['vote2'];
                $vote = intval($vote2);
                $value = 2;
            }
            //Get Detail

mysql_query("SET NAMES 'utf8'");
mysql_query ("SET CHARACTER SET utf8");
mysql_query ("SET COLLATION_CONNECTION = 'utf8_general_ci'");

// get all products from products table
$res_detail = mysql_query("SELECT *FROM v_list WHERE id='$int_id'") or die(mysql_error());

if (mysql_num_rows($res_detail) > 0) {
 while ($row = mysql_fetch_assoc($res_detail)) {
    if($value ==1 )
     {
      $fark = $vote1 - $row["vs1_vote"];
        if($fark == 1)
       {
        $sum_vote =  $vote1 + $row["vs2_vote"] ;
        $v1_percent = round( ($vote1 *100 /  $sum_vote), 2);
         $v2_percent = 100 - $v1_percent;
        }
          else
         {
          echo "An error occoured";
           }
      }//value1
  if($value ==2 )
    {
      $fark = $vote2 - $row["vs2_vote"];
      if($fark == 1)
       {
        $sum_vote =  $row["vs1_vote"] + $vote2 ;
        $v2_percent = round(($vote2 *100 /  $sum_vote),2);
        $v1_percent = 100 - $v2_percent;

        }
          else
         {
          echo "An error occoured";
           }
    }//value2

 }//while
}//if
$date = date('Y-m-d H:i:s');

    $flag['code']=0;
    if($value ==1 )
    {
      if($r=mysql_query("UPDATE v_list SET vs1_vote='$vote',vs1_percent='$v1_percent',vs2_percent='$v2_percent',allvotes='$sum_vote' WHERE id='$int_id'",$con))
      {
        $flag['code']=1;
        echo"hi";
      }
    }
    if($value ==2 )
    {  
      if($r=mysql_query("UPDATE v_list SET vs2_vote='$vote',vs1_percent='$v1_percent',vs2_percent='$v2_percent',allvotes='$sum_vote' WHERE id='$int_id'",$con))
      {
        $flag['code']=1;
        echo"hi";
      }
    }

    print(json_encode($flag));

    mysql_close($con);
?>