As you design the application, you must consider three distinct roles:

• The user-the person who uses the system to perform daily tasks.
• The owner-the person responsible for database integrity and security.
• The developer-the person who builds the application.

Application User

The application user runs an application to accomplish tasks. A user enters information at the keyboard and watches the screen for responses. To a user, the application is the interface-the windows and dialog boxes that are displayed-and the information it retrieves. As a result, an application should provide information about the tasks and how to complete them. The information should be easy to read, interpret, and be logically organized.

Database Owner

The database owner is responsible for the integrity and security of the database structure and data. An owner's primary concern is that the application doesn't compromise the integrity of the database. For example, the application should make sure the user enters all required data, does not enter invalid data, and cannot delete important data. Another concern is security; the application should prevent unauthorized users from retrieving confidential data.

Application Developer

The application developer plans how the user, application, and database interact. If the developer is not the database owner, the database owner can help plan the application. Another resource is the user, who can provide valuable information for a successful design. After planning, the developer assembles the available parts of an application-the menus, windows, command files, and the database.