设U是所有属性的集合, X、Y、Z都是U的子集,且Z=U-X-Y。下列关于函数依赖和多值依赖的叙述中,哪些是正确的?
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
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正确答案: BCE 答案分析:无
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A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y
A.若X→→Y,则X→Y
B.若X→Y,则X→→Y
C.若X→→Y,则X→→Z
D.若X→Y,则X→Z
E.若YX,则X→→Y