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