Introduction
The purpose of this section is to look at the
general concepts which lie behind the subject of computer files before going on
to discuss the different methods of organizing them. At all times, the term
“file” will refer to computer data files.
general concepts which lie behind the subject of computer files before going on
to discuss the different methods of organizing them. At all times, the term
“file” will refer to computer data files.
A file holds data which is required for providing
information. Some files are processed at regular intervals to provide this
information (e.g. payroll file) and others will hold data which is required at
regular intervals (e.g. a file containing prices of items).
information. Some files are processed at regular intervals to provide this
information (e.g. payroll file) and others will hold data which is required at
regular intervals (e.g. a file containing prices of items).
There are two common ways of viewing files:
a.
Logical
files: “logical file” is a file viewed in terms of what data items its’
record contain and what processing operations may be performed upon the file.
Logical
files: “logical file” is a file viewed in terms of what data items its’
record contain and what processing operations may be performed upon the file.
b.
Physical
files: A “physical file” is a file viewed in terms of how the data is stored on
a storage device such as a magnetic disk and how the processing operations are
made possible. A logical file can usually give room to a number of alternative
physical file implementation.
Physical
files: A “physical file” is a file viewed in terms of how the data is stored on
a storage device such as a magnetic disk and how the processing operations are
made possible. A logical file can usually give room to a number of alternative
physical file implementation.
