:设关系模式R(ABCD),在R上的FD集F={A→B,B→C,C→D},分解r={AB,ACD}...答:1) R(A,B,C,D,E,F)F={A→BC,CF→DE,DE→BF} 求出candidate key candidate key: AC,AD,AF 2) R(A,B,C,D,E,F)F={A→BCD,D→EF} Decomposition: {R1=A B C D, R2=D E F} Is it a loss_less joint decomposition ?Since R1 Ç R2= D R2 – R1 =E F And ...