Question

我有一个名为data_tbl的mysql表，其中包含不同ID的行，如下所示

-----------+------------+----------+---------------------+-------------+
id   | date       | user | field               | change_from | change_to
-----------+------------+----------+---------------------+-------------+
7293 | 08/29/2017 | chey | Status              | M           | R        
7293 | 08/29/2017 | chey | File Name           |             | Diffs-com
7293 | 08/29/2017 | chey | Status              | V           | M        
7293 | 08/07/2017 | chey | Note Title          |             | static-an
2293 | 08/07/2017 | chey | File Name           |             | Diffs-com
7293 | 06/28/2017 | dets | Is-customer-visible | N           | Y        
7293 | 05/30/2017 | unmx | Status              | R           | V        
2293 | 05/24/2017 | chey | Bug-origin          |             | Code / Im
3593 | 05/24/2017 | chey | Regression          |             | N        
7293 | 05/24/2017 | chey | Status              | A           | R        
3293 | 05/24/2017 | chey | Note Title          |             | static-an
4293 | 05/24/2017 | chey | File Name           |             | Diffs-com
4293 | 05/24/2017 | chey | File Name           |             | Diffs-com
5293 | 05/22/2017 | chey | Note Title          |             | static-an
7293 | 05/22/2017 | chey | File Name           |             | Diffs-com
7293 | 04/28/2017 | gogi | Engineer            | gogi        | chey     
7293 | 04/25/2017 | dets | Is-customer-visible |             | N        
7293 | 04/25/2017 | itka | Assigner            |             | itka     
7293 | 04/25/2017 | itka | Engineer            |             | gogi     
7293 | 04/25/2017 | itka | Status              | N           | A        
7093 | 04/25/2017 | koga | Defect Created      |             |          
7393 | 04/25/2017 | vkal | Defect Created      |             |          
7293 | 04/25/2017 | vkal | Defect Created      |             |          
7293 | 04/25/2017 | vkal | Defect Created      |             |          
7293 | 04/25/2017 | vkal | Defect Created      |             |          
-----------+------------+----------+---------------------+-------------+

从上表中我如何编写一个自我过滤的查询，如下所示

select * from data_tbl where id in ('7293', '7093') and 
(from the filtered rows from above, filter when field is "engineer" change_to must be "chey" and when field is status change_from should be "A" and change_to should be "R")

我的目标是从上面过滤数据集，得到类似下面的内容

-----------+------------+----------+---------------------+-------------+
id   | date       | user | field               | change_from | change_to
-----------+------------+----------+---------------------+-------------+

7293 | 05/24/2017 | chey | Status              | A           | R        
7293 | 04/28/2017 | gogi | Engineer            | gogi        | chey     
-----------+------------+----------+---------------------+-------------+

Answer 1

你的病情

当字段是“工程师”时，change_to必须是“chey”

当字段为status时，change_from应为“A”，change_to应为“R”

您可以使用UNION结合两个选择查询。

SELECT ID,DATE,USER,field,change_from,change_to 
FROM
(
    SELECT ID,DATE,USER,field,change_from,change_to
    FROM data_tbl
    WHERE change_from = 'A' AND change_to = 'R'
    UNION
    SELECT ID,DATE,USER,field,change_from,change_to
    FROM data_tbl
    WHERE field = 'engineer' AND change_to = 'chey'
) AS A
WHERE A.ID in ('7293', '7093')

Answer 2

使用此作为描述

where id in ('7293', '7093') AND

... when field is "engineer" ... change_to must be "chey" OR ...

... when field is status ... change_from should be "A" and change_to should be "R")

SQL成为：

 select * from data_tbl where id in ('7293', '7093') 
  AND (
   (field = 'Engineer' AND change_to = 'chey') OR
   (field = 'Status' AND change_from = 'A' AND change_to = 'R') 
  );

Answer 3

根据您的要求和所需结果，您只需要select语句，其中包含一些过滤器和case语句，以生成所需数据：

SELECT id, date, user, field, 
       CASE WHEN field = 'Status' THEN 'A'
            ELSE change_from 
        END change_from
       CASE WHEN field = 'Engineer' THEN 'chey' 
            WHEN field = 'Status' THEN 'R'
            ELSE change_to 
        END change_to
 WHERE id IN ('7293', '7093')
   AND field IN ('Engineer', 'Status');

这将与您根据需要添加的结果完全相同。当然基于提供的样本数据。

Answer 4

这些只是过滤器，除了当你说“当......和（而不是）那个......”时，“和”实际上是一个逻辑OR，因为你想要两个条件都可以接受。 / p>

过滤字段为“工程师”时，change_to必须为“chey”

((`field` = 'Engineer' AND change_to = 'chey')

当字段为状态时，change_from应为“A”，change_to应为“R”

(`field` = 'Status' AND change_from = 'A' AND change_to = 'R'))

所以：

WHERE id IN (7093, 7293)
AND
(
    (`field` = 'Engineer' AND change_to = 'chey')
    OR
    (`field` = 'Status' AND change_from = 'A' AND change_to = 'R')
)

如果你想拥有那些状态和工程师系列，还有其他人（例如回归，分配者......），如果这些是最后几行，你可以明确命名：

    ...
    OR
    (`field` = 'Status' AND change_from = 'A' AND change_to = 'R')
    OR
    (`field` = 'Assigner')
    OR
    (`field` = 'Note Taken')

另一方面，如果有很多类型，通过指定“其他”可以更好地服务：带有既不是Statud也不是工程师的字段的记录。

    ...
    OR
    (`field` = 'Status' AND change_from = 'A' AND change_to = 'R')
    OR
    (`field` NOT IN ('Status', 'Engineer'))

Mysql过滤一个条件然后过滤不同的条件

4 个答案: