Question

所以我有以下查询

SELECT r.userId, r.programmeId, u.email, u.firstName, u.lastName, u.profileId, tblProgrammes.name, u.storeId, r.dateEnded AS lastPass, r.dateExpired
FROM tblUserRepeatHistory AS r INNER JOIN
tblUsers AS u ON r.userId = u.id INNER JOIN
tblProgrammes ON r.programmeId = tblProgrammes.id
WHERE (r.dateExpired IS NOT NULL) AND (u.storeId = @storeId)
GROUP BY r.userId, r.programmeId, u.email, u.firstName, u.lastName, u.profileId, tblProgrammes.name, u.storeId, r.dateEnded, r.dateExpired, r.id
HAVING (DATEDIFF(D, MAX(r.dateExpired), GETDATE() + 31) >= 0)

返回以下数据

11 22 asdf@asdf.com store-mgr jamie2 1 Deli Food Service 1 5 04/02/2011 09:36:11 10/05/2011 09:36:11

11 22 asdf@asdf.com store-mgr jamie2 1 Deli Food Service 1 5 04/02/2011 09:36:11 10/05/2011 09:36:11

11 22 asdf@asdf.com store-mgr jamie2 1 Deli Food Service 1 5 11/05/2011 09:44:36 10/07/2011 09:44:36

11 23 asdf@asdf.com store-mgr jamie2 1 Deli Food Service 2 5 11/05/2011 10:12:50 16/06/2011 10:12:50

我基本上只为每个用户和程序返回了1条记录，其中最近添加的一条应该返回，所以我猜是MAX（dateExpired）。所以这个查询应该只返回两个记录

11 22 asdf@asdf.com store-mgr jamie2 1 Deli Food Service 1 5 11/05/2011 09:44:36 10/07/2011 09:44:36
11 23 asdf@asdf.com store-mgr jamie2 1 Deli Food Service 2 5 11/05/2011 10:12:50 16/06/2011 10:12:50

Answer 1

SELECT DISTINCT是您需要的SQL关键字。 DISTINCT导致查询仅返回不同的列

Answer 2

从GROUP BY子句中删除r.dateExpired，并将其替换为选择列表中的“MAX（r.dateExpired）as dateExpired”。

Answer 3

您可以使用交叉申请

SELECT * FROM tblUsers as u CROSS JOIN tblProgrammes p
CROSS APPLY
(SELECT TOP 1 dateExpired FROM tblUserRepeatHistory
WHERE userId = u.id and programmeId = p.id
ORDER BY dateExpired desc
) as rr

在共同相关的子查询中，您可以在tblUserRepeatHistory中获得最大dateExpired，其中符合程序和用户，对于嵌套查询和表值函数，交叉应用就像内连接一样

从查询中删除重复项

3 个答案: