Mysql查询结果自动添加序号

直接上例子了，查询近一周TOP20的订单商品。

   mysql> select (@ii:= @ii+1) as "序号", otmp.* from (select sku_id as "SKU_ID",count(*) as "数量" from order where  order_time BETWEEN DATE_SUB(CURDATE(), INTERVAL 7 DAY) and CURDATE() group by 1 order by 2 desc limit 20) otmp,(SELECT @ii:=0) as ii
;
+------+--------------+----+
| 序号   | SKU_ID       | 数量 |
+------+--------------+----+
| 1    | 100115 | 212  |
| 2    | 572205  | 139  |
| 3    | 533736  | 112  |
| 4    | 13206  | 88  |
| 5    | 5259     | 68  |
+------+--------------+----+