Concepts

All of these concepts are concerned with the process of analyzing your problem domain and deciding what fields to include in each table and what tables to include in each database.

A database is a collection of data and objects related to a particular topic or purpose. If you notice different kinds of unrelated data for different things in your problem domain, this is an indication that you may need more than one database. For example, recipes don't belong in a household inventory database. If you want to keep track of recipes and keep a household inventory, create two databases.

Tables hold the data in your database. A database includes one or more tables. We already talked about how to identify the fields you want to include in your database, but how do you decide what tables you should place the fields in? How many tables should you create? The fields in a table should form a dataset. That is, the fields of a record should be cohesive, with no duplication. For example, if you are creating a database to track sales in a small business you will most likely want to have two tables, one to hold customer information and another to hold customer orders. If you combined the information into one table you would have to duplicate the customer information for each order. For more information about creating multiple tables see the related concept.