Each form displays a set of fields of the database

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Unformatted text preview: erator can also be instructed to perform arithmetic operations (such as calculating subtotals and totals) on the data found in numeric fields to make a report more meaningful and useful. A user can define the layout of a report and then store it for later use. This facility is often used for generating periodic reports. For example, this facility is found to be very useful for generation of employee pay-slips from an employee database every month, or generation of consumer bills every month, for the consumers of a service. The report layout format remains the same every month, only the data changes. Creating and Using a Database In this section we will have a closer look at how a database is created and used. Large databases on large computer systems are normally created and maintained by professional programmers. The users of these databases, however, need not be programmers. They can be easily used by non-programmers to access the data and produce reports. On the other hand, many database management systems designed for personal computer systems enable non-programmers to not only use but even to create their own databases. These databases are normally simple in structure and small in size. Creating a Database Creation of a database is a three steps process: 1. Defining its structure, (schema), 2. Designing forms (custom screens) for displaying and entering data, and 3. Entering the data into it. These steps are briefly described below. Schema Definition The first thing we do to set up a database is to define its structure (schema definition). This is done by identifying the characteristics of each field in it. A good way to begin defining the schema of a database is to list down on paper all the fields that are to be included in the database, and then to determine the name, type, and size of each field. This information is then captured into the system using a tool called schema builder. The schema builder enables a user to define a database schema interactively by prompting the user to enter the field name, field type field size, and so on for each field. While defining the schema of a d...
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