帝国cms自定义函数之随机获取10条信息id

帝国cms用自定义函数随机获取10条信息id的代码
function jhc_get_keyid($tbname,$limit=10){
    global $empire,$dbtbpre;
    $maxid=$empire->gettotal("select max(id) as total from {$dbtbpre}ecms_{$tbname} ");
    $ids=array();
    $i=0;     
    while($i<$limit){
            $key=rand(1,$maxid);
            $key=$empire->gettotal("select id as total from {$dbtbpre}ecms_{$tbname} where id<=$key order by id desc limit 1 ");
            if(in_array($key,$ids))continue;
            $ids[]=$key;
            $i++;
    }
    $rand=implode(',',$ids);   
    return $rand;
}