Homework 2 Database concepts
Unit 4 Exchanging data
Homework 2 Database concepts
1. Define the following terms:
(a) Entity [1]
(b) Primary key [1]
(c) Secondary key [2]
(d) Foreign key [2]
2. A cinema club shows up to three screenings of films on a given day. They need a database
to keep track of which films have been shown on which dates. It has been suggested that
they use one table (relation) about the films they show, which will hold the following data:
FilmID, Title, Duration, Male Lead, Female Lead, Date shown, Time shown, Tickets sold.
(a) Give a reason why this is not a satisfactory solution. [1]
(b) Show how the data could be reorganised into four relations, using the notation
Entity name (attribute1, attribute2, attribute3 …)
An underscore indicates the primary key. The entities that have been identified are
Film,
Actor, ActorInFilm and Showing. [8]
1
Unit 4 Exchanging data
Homework 2 Database concepts
1. Define the following terms:
(a) Entity [1]
(b) Primary key [1]
(c) Secondary key [2]
(d) Foreign key [2]
2. A cinema club shows up to three screenings of films on a given day. They need a database
to keep track of which films have been shown on which dates. It has been suggested that
they use one table (relation) about the films they show, which will hold the following data:
FilmID, Title, Duration, Male Lead, Female Lead, Date shown, Time shown, Tickets sold.
(a) Give a reason why this is not a satisfactory solution. [1]
(b) Show how the data could be reorganised into four relations, using the notation
Entity name (attribute1, attribute2, attribute3 …)
An underscore indicates the primary key. The entities that have been identified are
Film,
Actor, ActorInFilm and Showing. [8]
1
