Q56,paper 3,D 12. If a relation with a Schema R is decomposed into two relations R1and R2 such that (R1+R2) = R1 then which one of the following is to be satisfied for a lossless joint decomposition (->indicates functional dependency)

(A) (R1 intersection R2)->R1

or

R1intersection R2->R2

(B) R1 intersection R2->R1

(C) R1 intersection R2->R2

(D) R1 intersection R2->R1

and

R1 intersection R2->R2

Answer  A.

Lossless join decomposition method is

(R1 intersection R2)->R1

or

R1 intersection R2->R2