Question

Difference between tuple and domain relational calculus in tabular form

Answer 1

Domain relational calculus

It selects the attributes instead of a whole tuple,

List of attributes is selected according to the condition given.

Employee’s name and Id in department 2

{<EMP_ID, EMP_NAME> | <EMP_ID, EMP_NAME> ? EMPLOYEE Λ DEPT_ID = 2}

Tuple relational calculus

It selects tuple in a relationship.

It uses range of values and certain attributes values to select tuple.

The employee in department 2

 {t | EMPLOYEE (t) AND t.DEPT_ID = 2} 

The variable(t) used, called tuple variable.