两表关联问题？

[rgb_rgb]

有两个表A，B
A表
y1 y2
1 dd
2 df
3 dt
4 ss
.......

B表
w1 w2
1 2005
4 2004
........

要得到C表

y1 y2 w2
1 dd 2005
2 df
3 dt
4 ss 2004

注：无论B表中有没有A表中的数据，A表中的数据全部要显示?

[splory]

select y1 , y2 , w2 from A left join B on A.y1=B.w1

[hellowork]

select a.y1,a.y2,b.w2 from A as a left join B as b on a.y1 = b.w1

[lxzm1001]

left join

[wuguang007]

SELECT Y1,Y2,W2 FROM A,B WHERE A*=B

[wuguang007]

SELECT Y1,Y2,W2 FROM A,B WHERE A.y1*=B.w1

[rgb_rgb]

这个我试个，就是还有几张表要关联？用表A表中的y1,

[rgb_rgb]

就会有很多相同的数据

[liangfei1983]

select a.*,b.w2 from a left join b on a.y1=b.w1

[xyxfly]

就会有很多相同的数据


可以考虑distinct

或者group by

楼主还是具体点

也可以自己多试试连接

[rgb_rgb]

SELECT A.NetID,
B.UserName,
B.Address,
B.Telephone,
C.AccState,
D.Enddate

FROM dbo.B,dbo.C,dbo.A left outer join dbo.D on A.BusinessID = D.BusinessID

where B.UserID = A.UserID and
B.UserID = C.UserID and
A.BusinessID = C.BusinessID --and
--A.BusinessID = D.BusinessID
其中D表中有些数据不在A表中，但要显示出来A，B,C表中的信息?

[rgb_rgb]

给一条比较完整的，

[hellowork]

这样试试:
SELECT isnull(A.NetID,D.NetID),
B.UserName,
B.Address,
B.Telephone,
C.AccState,
D.Enddate

FROM dbo.B,dbo.C,dbo.A FULL join dbo.D /*使用FULL JOIN*/
on A.BusinessID = D.BusinessID

where B.UserID = A.UserID and
B.UserID = C.UserID and
A.BusinessID = C.BusinessID

[hellowork]

抱歉,更正一下:
SELECT A.NetID,
B.UserName,
B.Address,
B.Telephone,
C.AccState,
D.Enddate

FROM dbo.B,
inner join dbo.C on B.UserID = C.UserID
inner join dbo.A on B.UserID = A.UserID
left join dbo.D on A.BusinessID = D.BusinessID /*使用LEFT JOIN*/

----或
SELECT isnull(A.NetID,D.NetID),
B.UserName,
B.Address,
B.Telephone,
C.AccState,
D.Enddate

FROM dbo.B,
inner join dbo.C on B.UserID = C.UserID
inner join dbo.A on B.UserID = A.UserID
full join dbo.D on A.BusinessID = D.BusinessID /*使用FULL JOIN*/