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Unformatted text preview: sses the data stored in these files to generate the desired
output. For example, it is customary to set up a master file of permanent (and,
usually, the latest) data, and to use transaction files containing data of a temporary
nature. For instance, in a payroll processing application, the master payroll file
will contain not only all the permanent details about each employee, his/her name,
address, employee code, pay-rate, income tax rate, and so forth, but also the
current gross-pay-to-date total and the tax paid-to-date total. The transaction
payroll file will contain details of hours worked this week, normal and overtime,
and if piecework is involved, the quantity of goods made. When the payroll
program is processed, both files will have to be consulted to generate this week's
pay-slips, and the master file updated in readiness for the following week.
In the file-oriented approach of organizing data, a set of programs is provided to
facilitate the users in organizing, creating, deleting, updating, and manipulating
their files. All these programs together form a File Management System (FMS).
We will have a look at the commonly supported features in a typical file
management system in the next section of this chapter.
The file-oriented method of organizing data for data processing applications is
simple, inexpensive, and usually easy to use. However, it suffers from the
following limitations: 1. Limited query flexibility. In file-oriented approach, the records in a file are
organized according to a key field. As long as we search records based on key
field value, the query can be processed quickly. However, when the key field is
not relevant to the information needed, the entire file has to be searched. For
example, if the key field is employee code in an employee file, and if we need to
list out the names of all employees with a certain educational background, a search
of all the file records will be required to produce this information.
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This document was uploaded on 04/07/2014.
- Spring '14