What is a database?

A database provides for the storing and control of business data. It is independent from (but not separate from the processing requirements of) one or more applications. If properly designed and implemented, the database should provide a single consistent view of the business data, so that it can be centrally controlled and managed.

One way of describing a logical view of this collection of data is to use an entity relationship model. The database records details (attributes) of particular items (entities) and the relationships between the different types of entities. For example, for the stock control area of an application, you would have Parts, Purchase Orders, Customers, and Customer Orders (entities). Each entity would have attributes--the Part would have a Part No, Name, Unit Price, Unit Quantity, and so on.

These entities would also have relationships between them, for example a Customer would be related to orders placed, which would be related to the part that had been ordered, and so on. Entities, attributes, and relationships illustrates an entity relationship model.

Entities, attributes, and relationships

A database management system (DBMS), such as the IMS Database Manager (IMS/DB) component or the DB2 product, provides a method for storing and using the business data in the database.