关系模式R(A1,A2,A3,A4,A5),如果(A1,A2)→A3,(A3,A4)→A5, 则R的候选键为_________。? (A1, A2, A4, A5)。|(A1,A2,A4);;|(A1,A2,A5);|(A1,A2);;
关系模式R(A1,A2,A3,A4,A5),如果(A1,A2)→A3,(A3,A4)→A5, 则R的候选键为_________。? (A1, A2, A4, A5)。|(A1,A2,A4);;|(A1,A2,A5);|(A1,A2);;
发布时间:2024-12-29 00:03:15