[英]SQL Join to only one record in one to many relationship
我有以下查詢:
SELECT c.[ClientID]
,u.[AccessId]
FROM [tblClient] c
INNER JOIN [tblUser] u ON u.[Id] = c.[UserId]
此tblUser的每個UserID行都有多個ID。
所以它看起來像這樣:
UserID AccessID
1 AD2F0A-965B78414-2B34906F2-0127AA5A
1 ID2F0A9-65B784-142B34906-F20127AA5A
1 UD2F0A9-65B78-4142B34906F-20127AA5A
2 TD2F0A9-65B784142-B34906F-20127AA5A
2 RD2F0A9-65B784142B3-4906-F20127AA5A
3 WD2F0A96-5B784142-B34906F201-27AA5A
3 ZD2F0A96-5B784-142B34-906F2-0127AA5A
3 CD2F0A965-B784142B3-4906F20-127AA5A
有沒有一種方法只能獲取每個UserID的最高(或1)AccessId? 我得到哪個AccessID都沒有關系,我只想要其中一個。
謝謝
SELECT c.[ClientID], MAX(u.[AccessId])
FROM [tblClient] c
INNER JOIN [tblUser] u
ON u.[Id] = c.[UserId]
GROUP BY c.[ClientID]
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