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The Relational Database Model

This is an approach where we consider our collections of information about objects as Tables. A table is another name for Relation hence the term Relational database. Here is our DVD collection held as a table:

Serial No Title Year Director Genre Runtime Certificate Actor 1 Actor 2
0001 Alien 1979 Ridley Scott SciFi 117 18 John Hurt Sigourney Weaver
0002 Godfather 1971 Stanley Kubrick Drama 175 18 Marlon Brando Al Pacino
0003 Jaws 1975 Stephen Spielberg Drama 124 15 Robert Shaw Richard Dreyfuss
0004 The Matrix 1999 Andy Wachowski SciFi 136 15 Keanu Reeves Laurence Fishburne
0005 Jurassic Park 1993 Stephen Spielberg SciFi 127 PG Sam Neill Laura Dern
0006 Life of Brian 1979 Terry Jones Comedy 94 15 Graham Chapman John Cleese

This is a database comprising a single table representing the data we hold on all of our DVDs. You can think of a table as a template or place-holder. A database may contain more than one table. As we will see relational database packages such as Microsoft's Access provide facilities for us to create tables such as this.

You will see that we can ask this database questions (queries) such as "Give me a list of all films directed by Stephen Spielberg" which would return the result Jaws and Jurassic Park.

Another query might be "Display a list of SciFi files with runtime greater than 120 minutes" which would produce the result The Matrix and Jurassic Park.

Next: Database Example