How would you set up a database for your collection of movie DVD's? At
first, it would appear that you could just use an Excel spreadsheet. Each
movie has one title, one date of release. You could then just sort by movie
title, or date of release, depending on how you want to look up information.
However, what if you want to keep track of the actors that are in the movie?
You could just put those names in extra columns, but then you would have to
sort multiple times, once for each column, to find a particular actor's name.
Normalization is a process where you limit the data, so that you don't have
duplicate information entered. In a DVD database, you would have a table
that includes the title and date of release, and another table that includes
the names of actors. You then have a third table that will combine a unique
movie with a unique actor. You could have some movies that do not match with
any actors, or movies that match with 20 actors. You do not need to enter
movie names more than once, or actor's names more than once. They are
normalized.
You can now sort by movie, and see all the actors associated with that
movie, or sort by actor, and see all the movies associated with that actor.
Normalization is what separates a database from a spreadsheet. In a
spreadsheet, you have to duplicate information, and some types of information
will be difficult to search, sort or filter on. A spreadsheet requires that
data be stored in rows and columns, with one piece of data per cell. A
database allows you to "stack" data quickly and efficiently, and place many
pieces of data into what would be a single cell on a spreadsheet.
