Question

一段时间以来，我一直在努力进行这种查询/查询设计，我认为是时候咨询专家了！这是我的表格结果：

ID   | Status       | date         |
---------------------------------
05   | Returned     | 20/6/2018    |
03   | Sent         | 12/5/2018    |
01   | Pending      | 07/6/2018    |
01   | Engaged      | 11/4/2018    |
03   | Contacted    | 16/4/2018    |
05   | Surveyed     | 04/3/2017    |
05   | No Contact   | 05/3/2017    |

如何获取每个ID的最高/最新值：

ID   | Status       | date         |
---------------------------------
05   | Returned     | 20/6/2018    |
03   | Sent         | 12/5/2018    |
01   | Pending      | 07/6/2018    |

我尝试了分组方式，TOP 1，不同，结果仍然不是我想要的。另外，由于ID可以超过3种类型，因此也不显示前5％的结果。

以下我的查询：

INSERT INTO TmpAllcomsEmployee ( StatusID, EmployeeID, CommunicationDate )
SELECT DISTINCT CommunicationLog.StatusID, TmpAllcomsEmployee.EmployeeID, 
Max(CommunicationLog.CommunicationDate) AS MaxOfCommunicationDate
FROM CommunicationLog RIGHT JOIN TmpAllcomsEmployee ON 
     CommunicationLog.EmployeeID = TmpAllcomsEmployee.EmployeeID
GROUP BY CommunicationLog.StatusID, TmpAllcomsEmployee.EmployeeID
ORDER BY Max(CommunicationLog.CommunicationDate) DESC;

Answer 1

一种方法是相关子查询：

select cl.*
from CommunicationLog as cl
where cl.date = (select max(cl2.date)
                 from CommunicationLog as cl2
                 where cl2.EmployeeID = cl.EmployeeID
                );

这将获取CommunicationLog中每位员工的最新记录。如果确实需要，可以加入另一个表。除非您将其用于过滤，否则似乎没有必要。

选择每个记录的最高值

1 个答案: