Question

Consider the relations, City (city_name, state) and Hotel (name, address, city_name). Write the result of the following relational algebra expressions.

1. σ _{Departments=“Sales”}(EMPLOYEE). 

2. σ _{salary> 20000 ∧ Department = “Sales”}(EMPLOYEE). 

3. σ _{Salary>20000 ∨ Department = “Sales”}(EMPLOYEE). 

4. π _{name, salary}(EMPLOYEE). 

5. π _{name, salary}(σ _{Designations=“Manager”}(EMPLOYEE)). 

6. π _{name, Department}(σ _{Designation = “Clerk” salary > 20000}(EMPLOYEE)).

Answer 1

1.

Emp. Code	Name	Department	Designation	Salary
1001	Dhanya	Sales	Manager	25000
1002	Shajan	Sales	Clerk	13000

2.

Emp. Code	Name	Department	Designation	Salary
1001	Dhanya	Sales	Manager	25000

3.

Emp. Code	Name	Department	Designation	Salary
1000	Sudheesh	Purchase	Manager	25000
1001	Dhanya	Sales	Manager	25000
1003	Shajan	Sales	Clerk	13000

4.

Name	Salary
Sudheesh	25000
Dhanya	25000
Fathima	12000
Shajan	13000

5. 

Name	Salary
Sudheesh	25000
Dhanya	25000

6. No rows selected.