Question

Consider the following relation R(A,B,C,D,E,G) and the set of functional dependencies

F = { A → BCD

BC → DE

B → D

D → A}

Give a 3NF decomposition of the given schema based on a canonical cover

Answer 1

1. Remove D from BC->DE

2. A->BCD, BC->DE, B->D, D->A

3. Remove D from A->BCD

   A->BC, BC->E, B->D, D->A

4. Decompose A->BC

   A->B, A->C, BC->E, B->D, D->A

5. Remove C from BC->E

   ? : B->D->A->C => B->C => B->BC->E => B->E ? : B+:: B->BD->ABD->ABCD->ABCDE (E is an element of B+) A->B, A->C, B->E, B->D, D->A