SQL查询以获取不匹配具有空值的一个或多个字段的记录

时间:2018-10-24 13:25:37

标签: sql database ms-access

我正在尝试在访问中编写一个SQL查询,比较两个表。查询是将一个表中的最新数据与另一表中的旧数据进行比较。例如;

表1(新数据)

/------------------------------------------------------------------------\
| ID | Status     | ProductID | Request Date | ReqReviewed | Closed Date |
|----+------------+-----------+--------------+-------------+-------------|
| 1A | Successful |   0001    | 09/10/2000   |     Yes     | 09/20/2000  |
| 1A | Pending    |   0002    | 09/10/2000   |     Yes     |             |
| 2C | Successful |   0001    | 07/20/2001   |     Yes     | 07/29/2001  |
| 3A | Pending    |   0003    | 03/01/2002   |     Yes     |             |
| 3A | Pending    |   0002    | 03/01/2002   |     Yes     |             |
| 4A | Pending    |   0001    | 04/09/2002   |             |             |
| 5B | Successful |   0005    | 04/08/2001   |     Yes     | 05/20/2001  |
| 6F | Created    |   0001    |              |             |             |
\------------------------------------------------------------------------/

表2(旧数据)

/------------------------------------------------------------------------\
| ID | Status     | ProductID | Request Date | ReqReviewed | Closed Date |
|----+------------+-----------+--------------+-------------+-------------|
| 1A | Pending    |   0001    |  09/10/2000  |     No      |             |
| 1A | Pending    |   0002    |  09/10/2000  |     No      |             |
| 2C | Successful |   0001    |  07/20/2001  |     Yes     | 07/29/2001  |
| 3A | Returned   |   0003    |  03/01/2002  |     Yes     |             |
| 3A | Pending    |   0002    |  03/01/2002  |     No      |             |
| 4A | Created    |   0001    |              |             |             |
| 5B | Successful |   0005    |  04/08/2001  |     Yes     | 05/20/2001  |
\------------------------------------------------------------------------/

*** ID和ProductID将保持不变,并且ID可以包含具有不同ID的重复项,反之亦然。其他字段每天都可以更改。

我试图仅获取从前一天(表2)开始更改的记录(表1),特别是可以在前一天为空然后在第二天填充的字段(请求日期,ReqReviewed等) 。任何帮助将不胜感激!

0 个答案:

没有答案
相关问题