Y
ydzi_
Unregistered / Unconfirmed
GUEST, unregistred user!
D表<br>DID DMemo<br>D1 ...<br>D2 ...<br>D3 ...<br><br>C表<br>CID BInfo C1 C2 C3 DID<br>C1 ... 1 2 3<br>C2 ... 4 5 6<br><br>V表<br>VID VNum VInfo1 VInfo2 EID<br>V1 1 ... <br>V2 4 ...<br><br>E表<br>EID EName<br>E1 ...<br>E2 ...<br><br><br>SELECT A.AMemo AS AMemmo, C.CInfo1 AS 'CInfo1', C.CInfo2 AS 'CInfo2',E.EName AS EName FROM A,B,C,D,E,V <br> WHERE B.AID = A.AID AND ((V.VNum = C.C1) OR (V.VNum = C.C2) OR (V.VNum = C.C3)) AND E.EID = V.EID<br> <br> 问题:<br> C表中有这个号码,那么这条记录才可能查出来!<br> <br> 现在如果我要查的这条记录在C表中不存在,那应该怎么做啊!谢谢