php防刷新计数器的代码(session方式)

`COUNTER` int(11) NOT NULL

<?php
/**
* 简单防刷新的php计数器
* edit www.jb200.com
*/
function counter()
{
     session_start();
     $sql="select COUNTER from table_name";
     $result=mysql_db_query("db_name",$sql);
     if(!empty($result))
     {
         $row=mysql_fetch_array($result);
         $counter=++$row['COUNTER'];
         if(!$_SESSION['counter'])
         {
              $query="update table_name set COUNTER='".$counter."'";
              $result=mysql_query($query);
              if($result)
              {
                   //为session付值
                   $_SESSION['counter']=true;
              }
         }
        //输出访问者的数量
        echo $counter;
     }
} 
?>