Sql server SQL根据两列的最大值选择所有列
我有一张这样的桌子Sql server SQL根据两列的最大值选择所有列,sql-server,Sql Server,我有一张这样的桌子 PkReferencesID FkReferencesID DocID FKHRSEmployeeID AssignedDate AssignedTime FKActivityID 40855 NULL 8530 13 13920625 0829 1 40856 40855 8530 438
PkReferencesID FkReferencesID DocID FKHRSEmployeeID AssignedDate AssignedTime FKActivityID
40855 NULL 8530 13 13920625 0829 1
40856 40855 8530 438 13920625 0829 1
40857 40856 8530 13 13920625 0829 2
40858 40857 8530 438 13920625 0830 1
40859 40858 8530 NULL 13920625 0830 1
NULL NULL NULL NULL NULL NULL NULL
如何为每个FKHRSEmployeeID选择DocID=8530、FKActivityID=1、最大AssignedDate和最大AssignedTime的行
注意:对于每个FKHRSEmployeeID,结果应为一行
任何帮助都将受到感谢。谢谢
结果一定是这样
PKReferenceId FKReferenceId DocID FKHRSEmployeeID AssignedDate AssignedTime FKActivityID
40855空8530 13 13920625 0829 1
40858 40857 8530 438 13920625 0830 1查询2将检索您所请求的信息: 查询1:此查询获取每个员工的最大分配日期/时间
SELECT FKHRSEmployeeID, MAX(AssignedDate & AssignedTime)
FROM Table
WHERE T.DocID=8530
AND T.FKActivityID=1
GROUP BY FKHRSEmployeeID;
Query2:此查询使用前一个查询仅检索匹配的记录
SELECT T.*
FROM Table AS T
INNER JOIN Query1 AS Q
ON (T.Date=LEFT(Q.MaxDateTime,8))
AND (T.Time=RIGHT(Q.MaxDateTime,4))
AND (T.FKHRSEmployeeID=Q.FKHRSEmployeeID)
WHERE T.DocID=8530
AND T.FKActivityID=1;
此查询本身并不保证每个员工只能获得一条记录,除非FKHRSEmployeeID/AssignedDate/AssignedTime组合在表中是唯一的。您可以通过基于这些列创建唯一索引来确保这一点。最简单的方法是使用
行号()
您希望从示例表中获得什么结果集?
select t.*
from (select t.*,
row_number() over (partition by FKHRSEmployeeID
order by AssignedDate desc, AssignedTime desc
) as seqnum
from t
where DocID = 8530 and FKActivityID = 1
) t
where seqnum = 1