Answer to Question #44389 in Databases | SQL | Oracle | MS Access for moses

Question

Consider the relations
EMPLOYEE(emp#, name)
5+5
10
ASSIGNED_TO(project#, emp#)
PROJECT(project#, project_name, chief)
Express the following queries in Relational Algebra
(i) Get details of employee working on both comp354 and comp345 project numbers.
(ii)Find the employee number of employee who do not work on project comp678

Answer 1

Consider the relations
EMPLOYEE(emp#, name)
5+5
10
ASSIGNED_TO(project#, emp#)
PROJECT(project#, project_name, chief)
Express the following queries in Relational Algebra
(i) Get details of employee working on both comp354 and comp345 project
numbers.
(ii)Find the employee number of employee who do not work on project
comp678
Ans:(i) EMPLOYEE (ASSIGNED TO project # (σ(project#=’comp351’ ∨ project#=’comp 345 ASSIGNED _TO)))
Ans: (ii) TEmp#(EMPLOYEE)-TEmp#(project#=’c 678’ ASSIGNED_TO))