已知關聯( relation) T( A, B, C, D, E, F),
其函數相依集( functional dependency set)
F = {B → D, C → A, AD → F},
下列何者為T 之無損分解( lossless decomposition) ?
( A) T1 = {A, B, C, D}, T2 = {A, D, E, F}
( B) T1 = {A, B, C, F}, T2 = {B, C, D, E}
( C) T1 = {A, C, D, F}, T2 = {B, C, E, F}
( D) T1 = {A, D, E, F}, T2 = {B, C, D, F}
請問要怎分解?
我的想法
B->D
C->A 可分為CD->AD
AD->F
CD->AD->F 等於 CD->F
Orz
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 218.172.91.9