Which of the following is not an operator of relational algebra

The correct answer is (d). Square is not an operator of relational algebra.

Relational algebra is a formal system for manipulating relations. It is a mathematical model for relational databases and provides a theoretical foundation for relational database theory.

The basic operators of relational algebra are:

• Selection (σ): Selects tuples from a relation that satisfy a given condition.
• Projection (π): Projects a relation onto a subset of its attributes.
• Union (∪): Combines two relations into a new relation that contains all tuples from both relations.
• Intersection (∩): Combines two relations into a new relation that contains only the tuples that are in both relations.
• Difference (∖): Combines two relations into a new relation that contains all tuples from the first relation that are not in the second relation.
• Cartesian product (×): Creates a new relation that contains all possible pairs of tuples from the two relations.
• Equi join (⋈): Creates a new relation that contains all tuples from the two relations that have matching values on a specified set of attributes.

The square operator is not an operator of relational algebra. It is a mathematical operator that is used to calculate the square of a number.