if(!is_array($by_way)) $by_way = array($by_way);
if($by_way)$db->whereIn('by_way',$by_way);

if($by_way && !is_array($by_way)) $by_way = array($by_way);
if($by_way)$db->whereIn('by_way',$by_way);

这两对结果是不一样
第一组第二句始终都走了，你说气不气，反正我遇到了