if($orderby == 'down') 

{ 

$sql = "select SUM(downloads) as down_num,id from dede_downloads group by id ORDER BY down_num DESC LIMIT 0,15"; 

$dsql->Execute('me',$sql); 

while($drow = $dsql->GetArray() ) 

{ 

$arr[] = $drow['id']; 

} 

$dstr = implode(",",$arr); 

if($orwhere!='') 

{ 

$orwhere .= " AND arc.id in($dstr)"; 

}else{ 

$orwhere .= " where arc.id in($dstr)"; 

} 

$ordersql = 'ORDER BY field(arc.id,'.$dstr.')'; 

}