@@@ Let R be a relation with schema (A_1, A_2, ..., A_n, B_1, B_2, ....B_ m) and

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Let R be a relation with schema (A_1, A_2, ..., A_n, B_1, B_2, ....B_ m) and let S be a relation with schema (B_1, B_2, ....B_m); so that the attributes of S are a subset of the attributes of R. The quotient of R and S, denoted R S, is the st of tuples t over attributes A_1, A_2, ..., A_n such that for every tuple s in S, the tuple ts, consisting of the components of t for A_1, A_2, ..., A_n and the components of s for B_1 B_2, ....B_m is a member of R. Give an expression of relational algebra, using the operators we have defined before in this section, that is equivalent to R S. Another algebraic way to express a constraint is E_1 = E_2, where both E_1 and E_2 are relational-algebra expressions. Can this form of constraint express more than two forms ? Suppose R is a relation with attributes A_1 A_2, ... A_n

Explanation / Answer

1)Ans:

From the given information A , A , …..,A andB , B , ….B ) arethe attributesof Rand alsoB , B , ….B are the attributes of S. Result is A , A , …..,A (R S).

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