Question

A task of analyzing database is given to the Database Administrator of the company having the following relational database and give an expression in relational algebra each of the following queries:

Employee (person-name, street, city)

Works (person name, company name, salary)

Company (Company name, city)

Managers (person name, manager-name)

Convert these relations into ER model and specify Primary Key, Foreign Key, Candidate Key and Super Key in these relations.

Answer 1

Answer:

The company has wisely chosen to hire you as a database designer (at your usual consulting fee of. $2,500/ day). Each musician that records at Notown has an SSN,.

Answer 2

Foreign_ key: person name, city

Primary key: Company name

Explanation:

A primary key constrain is a column or group of columns that uniquely identifies every row in the table of the relational database management system.

The Foreign key is a column that creates a relationship between two tables.

The foreign key here is person name and city that is building a relationship between employee , works and Manager table.

While the company name has to be unique hence, it cannot be taken by someone so it is a primary key.