Question

Explain the following terms in the context of relational algebra.

(1) Cartesian product

(2) union-compatible

Answer 1

1)cartesian product:

cartesian product operation combines two or more tables into one table

notation :relation1 x relation2 x relation3 x - - - - - xrelatiojn n

here relation1 and relation2 - - - - - are relations.

example query:

σ'bid=2'(Books Χ Articles)

2) Union-compatible:

Union-compatible do the binary union between two given relations

Notation:r U s

Here r and s are two relation.

note:when we perform the binary union we should make sure that both relations have same number of attributes and contain same data type attributes.