MySQL union all排序問題

(select t1.goods_id  goods_id from 1dcq_goods t1 order by t1.goods_id )
UNION all

(select t2.goods_id  goods_id from 1dcq_goods t2 order by t2.goods_id desc )

如上sql語句，結果如下，可以看出是沒有順序的：

下面語句：

(select t1.goods_id  goods_id from 1dcq_goods t1 order by t1.goods_id limit 999999999 )
UNION all
(select t2.goods_id  goods_id from 1dcq_goods t2 order by t2.goods_id desc limit 999999999)

結果如下，可以看出是排序的，一個升序，一個降序，然后合並：

可見"limit"關鍵字不能少！