设有关系模式student(sno,sname,age),则约束"age BETWEEN 20 AND 40"属于()完整性规则。A.实体完
设有关系模式student(sno,sname,age),则约束"age BETWEEN 20 AND 40"属于()完整性规则。
A.实体完整性规则
B.参照完整性规则
C.用户定义的完整性规则
D.引用完整性规则
设有关系模式student(sno,sname,age),则约束"age BETWEEN 20 AND 40"属于()完整性规则。
A.实体完整性规则
B.参照完整性规则
C.用户定义的完整性规则
D.引用完整性规则
A、s_name
B、phone
C、gender
D、s_no
A、Students S# lname fname Class Telephone 1 Jones Allan 2 555-1234 2 Smith John 3 555-4321 3 Brown Harry 2 555-1122 5 White Edward 3 555-3344
B、
C、
D、
A、create view v_student as select * from student;
B、alter view v_student as select * from student;
C、drop view v_student as select * from student;
D、sp_help view v_student as select * from student;
A、select * into stufemal from student
B、select * into stufemal from student where ssex='女'
C、select * from student where ssex='女' into stufemal
D、select * from student into stufemal
A、πS#,C#(SC)÷πC#(σTNAME='LIU'(SC)) SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND NOT EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
B、πS#,C#(SC)÷πC#(σTNAME='LIU'(C)) SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND NOT EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
C、πS#,C#(SC)÷πC#(σTNAME='LIU'(C)) SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
D、πS#,C#(SC)÷πC#(σTNAME='LIU'(C)) SELECT DISTINCT S# FROM SC WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
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