Entity Relationship Diagram for Music Company

Question Source

Book: 

DATABASE MANAGEMENT SYSTEMS

Author:

Raghu Ramakrishnan

Johannes Gehrke

Scenario

Notown Records has decided to store information about musicians who perform on its albums (as well as other company data) in a database. The company has wisely chosen to hire you as a database designer (at your usual consulting fee of $2500/day).

• Each musician that records at Notown has an SSN, a name, an address, and a phone number. Poorly paid musicians often share the same address, and no address has more than one phone.
• Each instrument used in songs recorded at Notown has a unique identification number, a name (e.g., guitar, synthesizer, flute) and a musical key (e.g., C, B-flat, E-flat).
• Each album recorded on the Notown label has a unique identification number, a title, a copyright date, a format (e.g., CD or MC), and an album identifier.
• Each song recorded at Notown has a title and an author.
• Each musician may play several instruments, and a given instrument may be played by several musicians.
• Each album has a number of songs on it, but no song may appear on more than one album.
• Each song is performed by one or more musicians, and a musician may perform a number of songs.
• Each album has exactly one musician who acts as its producer. A musician may produce several albums, of course.

Design a conceptual schema for Notown and draw an ER diagram for your schema. The preceding information describes the situation that the Notown database must model. Be sure to indicate all key and cardinality constraints and any assumptions you make. Identify any constraints you are unable to capture in the ER diagram and briefly explain why you could not express them. 

ERD

Entity Relationship Diagram for Music Company Database