mysql - 按优先级排序的两列排序

Question

我必须显示下面按优先级排序的查询结果。

mysql> select CouponId, CouponCode, DateAdded, Priority from Coupon where IsFeatured=1 and IsApproved=1 order by DateAdded desc limit 12;
+----------+--------------+---------------------+----------+
| CouponId | CouponCode   | DateAdded           | Priority |
+----------+--------------+---------------------+----------+
|    42699 | cc2          | 2013-09-12 14:54:39 |     NULL |
|    42698 | c1           | 2013-09-12 14:53:36 |     NULL |
|    42697 | cc2          | 2013-09-12 14:51:57 |     NULL |
|    42679 | GLMR20       | 2013-05-14 13:21:07 |        5 |
|    42678 | HKBAJAJ20    | 2013-05-14 12:35:31 |        1 |
|    42677 | SIPPER51     | 2013-05-14 12:11:36 |     NULL |
|    42654 | GL13MAYCHILL | 2013-05-14 07:09:08 |        7 |
|    41978 | POLARSPL     | 2013-05-03 13:31:32 |     NULL |
|    41958 | COMBO30      | 2013-05-03 12:16:53 |     NULL |
|    41357 | BRANDED60    | 2013-04-25 13:49:56 |     NULL |
|    41073 | PKCCR500     | 2013-04-22 11:10:27 |     NULL |
|    40794 | SWC15        | 2013-04-18 13:57:54 |     NULL |
+----------+--------------+---------------------+----------+
12 rows in set (0.00 sec)

我虽然按 Priority desc 的另一个订单可以做到这一点，但它会产生相同的结果

mysql> select CouponId, CouponCode, DateAdded, Priority from Coupon where IsFeatured=1 and IsApproved=1 order by DateAdded desc, Priority desc limit 12;
+----------+--------------+---------------------+----------+
| CouponId | CouponCode   | DateAdded           | Priority |
+----------+--------------+---------------------+----------+
|    42699 | cc2          | 2013-09-12 14:54:39 |     NULL |
|    42698 | c1           | 2013-09-12 14:53:36 |     NULL |
|    42697 | cc2          | 2013-09-12 14:51:57 |     NULL |
|    42679 | GLMR20       | 2013-05-14 13:21:07 |        5 |
|    42678 | HKBAJAJ20    | 2013-05-14 12:35:31 |        1 |
|    42677 | SIPPER51     | 2013-05-14 12:11:36 |     NULL |
|    42654 | GL13MAYCHILL | 2013-05-14 07:09:08 |        7 |
|    41978 | POLARSPL     | 2013-05-03 13:31:32 |     NULL |
|    41958 | COMBO30      | 2013-05-03 12:16:53 |     NULL |
|    41357 | BRANDED60    | 2013-04-25 13:49:56 |     NULL |
|    41073 | PKCCR500     | 2013-04-22 11:10:27 |     NULL |
|    40794 | SWC15        | 2013-04-18 13:57:54 |     NULL |
+----------+--------------+---------------------+----------+
12 rows in set (0.00 sec)

mysql> 

如何按优先级排序此查询的结果，以便优先级为 7 的行显示在顶部，而不管其添加日期如何？

我需要在查询中按 DateAdded 排序，以仅选择时间方面的前 12 行，然后根据优先级对它们进行排序。

Answer 1

select CouponId, CouponCode, DateAdded, Priority 
from
(
   select CouponId, CouponCode, DateAdded, Priority 
   from Coupon
   where IsFeatured=1 
   and IsApproved=1 
   order by DateAdded desc
   limit 12
) x
order by Priority desc