SQL只能在一对多关系中加入一条记录

Question

我有以下查询:

SELECT c.[ClientID]
        ,u.[AccessId]
 FROM [tblClient] c
 INNER JOIN [tblUser] u ON u.[Id] = c.[UserId]

此tblUser具有每个UserID行的多个ID.

所以它看起来像这样:

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

有没有办法只为每个UserID获取顶部(或1)AccessId？我得到哪个AccessID无关紧要,我只想要其中一个.

谢谢

Answer 1

SELECT c.[ClientID], MAX(u.[AccessId]) 
    FROM [tblClient] c 
        INNER JOIN [tblUser] u 
            ON u.[Id] = c.[UserId]
    GROUP BY c.[ClientID]