PHP判断数据库中的记录是否存在的方法

<?php 
 
$sql="select from checklist where game_id=$gid and task='$task' and status='$status'"; 
$result=mysql_query($sql); 
 
$row = mysql_fetch_array($result, MYSQL_ASSOC); 
 
    if (!mysql_num_rows($result)) 
        { 
            echo "record doesn't exist~~~~~!!!!!!"; 
        } 
    else 
        { 
           // echo mysql_num_rows($result)."\n"; 
            echo $row['game_id']; 
            echo $row['task']; 
        } 
?>