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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
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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- Spring '14