Difference between Relational Algebra and Relational Calculus

Relational Algebra

Relational algebra is a procedural query language, which takes instances of relations as input and yields instances of relations as output. It uses operators to perform queries. An operator can be either unary or binary. They accept relations as their input and yield relations as their output. Relational algebra is performed recursively on a relation and intermediate results are also considered relations.

The fundamental operations of relational algebra are as follows -

• Select

• Project

• Union

• Set different

• Cartesian product

• Rename

Relational Calculus

In contrast to Relational Algebra, Relational Calculus is a non-procedural query language, that is, it tells what to do but never explains how to do it.

Relational calculus exists in two forms -

• Tuple Relational Calculus (TRC)

• Domain Relational Calculus (DRC)

Following are some of the important differences between Relational Algebra and Relational Calculus.