共找到 945025 与dbeabletodoitbythisFriday. 相关的结果,耗时1877 ms
设有关系模式R(A,B,C,D,E,F),根据语义有如下函数依赖集:F={A→B,(C,D) →A,(B,C) → D,(C,E)→D,(A,E)→F)。则关系模式R的候选码是( )。A.(A,D,E)B.(C,D,E)C.(B,C)D.(C,E)
A.(C, B, D, A, P, E, I, J, G, H)B.(C, B, D, A, E, F, I, G, J, H)C.(B, A, D, E, F, G, I, J, H, C)D.(B, C, D, A, E, F, I, J, G, H)
A.(C, B, D, A, F, E, I, J, G, H)B.(C, B, D, A, E, F, I, G, J, H)C.(B, A, D, E, F, G, I, J, H, C)D.(B, C, D, A, E, F, I, J, G, H)
A.{A}{A,B,C,D,E}{A,B,C,D,E,F,G,H,I,J,K}B.{F}{G}{H}{I}{J}{K}{B,F,G}{C,H}{D,I,J}{E,K}{A,B,C,D,E,E,G,H,I,J,K}C.{K}{J}{I}{H}{G}{F}{B}{C}{D}{E}{A,B,C,D,E,
A.{A}{A,B,C,D,E}{A,B,C,D,E,P,G,H,I,J,K}B.{F}{G}{H}{I}{J}{K}{B,F,G}{C,H}{D,I,J}{E,K}{A,B,C,D,E,F,G,H,I,J,K}C.{K}{J}{I}{H}{G}{F}{B}{C}{D}{E}{A,B,C,D,E,
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