考虑关系R,它具有5个属性 ABCDE。 (1)对于下面的每

考虑关系R,它具有5个属性 ABCDE。
(1)对于下面的每个R的实例,指出它是否违反(a)函数依赖BC→D;(b)多值依赖BC→D
(a){}
(b){(a,2,3,4,5),(2,a,3,5,5)
(c){(a,2,3,4,5),(2,a,3,5,5),(a,2,3,4,6)
(d)((a,2,3,4,5),(2,a,3,4,5),(a,2,3,6,5)}
(e){(a,2,3,4,5),(2,a,3,7,5),(a,2,3,4,6)}
(f){(a,2,3,4,5),(2,a,3,4,5),(a,2,3,6,5),(a,2,3,6,6)}
(g){(a,2,3,4,5),(a,2,3,6,5),(a,2,3,6,6),(a,2,3,4,6)
(2)如果上面所列出的实例都是合法的,那么你怎么理解函数依赖A→B?