题目
A.hk
B.usa
C.uk
D.cn
第2题
Given the two relations X and Y below X: A B Y: C D 7 s t 1 3 z r 2 1 u what values would be retrieved by executing the following statement select X.A, X.B, Y.C from X, Y where X.A< y.d _________________
第3题
第4题
A.SELECT* FROM R WHERE <'2'
B.SELECTB, E FROM R WHERE B<'2'
C.SELECTB, E FROM R HAVING E<'2'
D.SELECT* FROM R WHERE '5'<B
第5题
A.SELECT A,B FROM R,S WHERE C<B
B.SELECT R.A,S.B FROM R,S WHERE R.C<S.B
C.SELECT 1,5 FROM R WHERE C<(SELECT B FROM S)
D.SELECT A,B FROM RWHERE C<(SELECT B FROM S)
第6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,D FROM R,S WHERE R=S
D.SELECT A,B FROM R WHERE(SELECT D FROM S WHERE R.C=S.C)
第7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)
第8题
A.SELECT*FROM R,SWHERE 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9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10题
设有关系R(A,B,C)和S(C,D)。与关系代数表达式πA,B,D(σR.C=S.C(R×S)等价的SQL语句是
A.SELECT*FROM R,S WHERE R.C=S.C
B.SELECT A,B,D FROM R,S WHERE R.C=S.C
C.SELE4T 1,2,8 FROM R,S WHERE R=S
D.SELECT A,B FROM R WHERE(SELECT D FROM S WHERE R.C=S.
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