具有特定条件的 MySQL 键值存储排序

Question

我有以下结构：

+----------+--------+---------------------+
| id| gr_id| name   | value               |
+----------+--------+---------------------+
| 1  |  11 | name   | Burro               |
| 2  |  11 | submit | 2019/05/10          |
| 3  |  11 | date   | 2019/05/17          |   
| 4  |  12 | name   | Ajax                |
| 5  |  12 | submit | 2019/05/10          |
| 6  |  12 | date   | 2019/05/18          | 
+----------+--------+---------------------+

我必须按日期排序（如果名称是日期），从最高到最低日期，还必须保留组（gr_id）而不混合元素。

想要的结果如下所示：

+----------+--------+---------------------+
| id| gr_id| name   | value               |
+----------+--------+---------------------+
| 4  |  12 | name   | Ajax                |
| 5  |  12 | submit | 2019/05/10          |
| 6  |  12 | date   | 2019/05/18          |   
| 1  |  11 | name   | Burro               |
| 2  |  11 | submit | 2019/05/10          |
| 3  |  11 | date   | 2019/05/17          | 
+----------+--------+---------------------+

我该如何实现？

Answer 1

您必须将组排序标准与组的所有元素相关联。您可以通过子查询或连接来完成。

子查询版本：

SELECT t.*
FROM (SELECT gr_id, value as `date` FROM t WHERE `name` = 'date') AS grpOrder
INNER JOIN t ON grpOrder.gr_id = t.gr_id
ORDER BY grpOrder.`date`
, CASE `name` 
   WHEN 'name' THEN 1 
   WHEN 'submit' THEN 2
   WHEN 'date' THEN 3
   ELSE 4
 END

加入版本：

SELECT t1.*
FROM t AS t1
INNER JOIN AS t2 ON t1.gr_id = t2.gr_id AND t2.`name` = 'date'
ORDER BY t2.value
, CASE t1.`name` 
   WHEN 'name' THEN 1 
   WHEN 'submit' THEN 2
   WHEN 'date' THEN 3
   ELSE 4
 END