投影 查询

[sql]代码库

SELECT T.TNo,TN,CNo
FROM T,TC
WHERE (T.TNo = TC.TNo)AND (TN='刘伟')
 
SELECT T.TNo,TN,CNo
FROM T,TC
WHERE(TN='刘伟')
 
SELECT S.SNo,SN,CN,Score
FROM S,C,SC
WHERE (S.SNo = SC.SNo)AND (SC.CNo=C.CNo)
 
SELECT S.SNo,SN,CN,Score
FROM S,C,SC
 
SELECT C.CNo,CN,COUNT(SC.SNo) as 选课人数
FROM C,SC
WHERE  (SC.CNo=C.CNo)
GROUP BY C.CNo,CN
 
SELECT C.CNo,COUNT(SC.SNo) as 选课人数
FROM C,SC
WHERE  (SC.CNo=C.CNo)
GROUP BY C.CNo
 
SELECT *
FROM S CROSS JOIN C
 
SELECT X.TN,X.Sal AS SaL_a,Y.Sal AS Sal_b
FROM T AS X ,T AS Y
WHERE  X.Sal>Y.Sal AND Y.TN='刘伟'

SELECT SN,Age,CN
FROM S,C,SC
WHERE S.SNo = SC.SNo AND SC.CNo = C.CNo