Tuple Relational Calculus in DBMS

Tuple Relational Calculus (TRC) in DBMS 

Relational calculus peoples are filtered based on a condition 

Syntax:

{ T | Condition } 

Relation part 

• Here t represents the tuple variable which is nothing but representing that it is a table 
• It can be any variable but for understanding we use variable t which stands for the table as per our context
• For example, if our table is Student, we would put it as Student(T)

Condition part 

Condition is specified using this dot variable the common and column we need to operate

Example  1

T.age > 22

• where T is our tuple variable and age is a column that is used for filtering the records in the relation 
• Now combine both relational and conditional part and see how the final quotation will look like T.name | Student(T) AND T.age > 21 
• It is a relational calculus which results in names of students from the table student for having age greater than 17 

Example 2 

{t | Employee (e) and e.SALARY > 100000} 

• Now, this represents results which will be returned as tuple t.
• Predicate here is – Employee (e) and e.SALARY > 100000 will return tuples for all the employees who have a salary greater than 100000. 

Example 3 

{ t | Employee (e) and Salary(t.emp_ID = s.emp_ID ∧ s.Salary >= 100000)} 

• It will result in the employeeId for each employee that has his/her salary  greater or equal to 10000.