题目
A.SELECT * FROM R,S WHERE R.C=S.C
B.SELECT A,B,D FROM R,S WHERE R.C=S.C
C.SELECT A,B,D FROM R,S WHERE R=S
D.SELECT A,B FROM R WHERE(SELECT D FROM S WHERE R.C=S.C)
第1题
A.∏A(R)
B.σB=17(R)
C.∏A(σB=17(R))
D.σB=17(∏A(R))
第2题
A.σR.C=S.C(πA,B,D(R×S))
B.πA,B,D(σR.C=S.C(R×S))
C.σ=((πA,B R)×(πDS))
D.σR.C=S.C(πD((πA,B(R))×S))
第3题
A.σR.C=S.C(πA,B,D(R×S))
B.πA,B,D(σR,C= S.C(R×S))
C.σR.C=S.C((πA,B (R))×(πD(S)))
D.σR,C=S.C(πD((πA,B(R))×S))
第4题
A.σR.C=S.C(πA,B,D(R×S))
B.πA,B,D(σR,C= S.C(R×S))
C.σR.C=S.C((πA,B (R))×(πD(S)))
D.σR,C=S.C(πD((πA,B(R))×S))
第5题
A.SELECT * FROM R,S WHERE R.C=S.C
B.SELECT A,B,D FROM R,S WHERE R.C=S.C
C.SELECT A,B,C FROM R,S WHERE R=S
D.SELECT A,B ,C FROM R WHERE C IN (SELECT C FROM S )
第6题
A.SELECT * FROM R,S WHERE R.C=S.C
B.SELECT B,D FROM R,S WHERE R.C=S.C
C.SELECT B,D FROM R,S WHERE R=S
D.SELECT B FROM R WHERE(SELECT D FROM S WHERE R.C=S.C)
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