Topics Covered: File Components of file Components of file Terms used Terms used Types of business file Types of business file Operations on file Operations on file

File  File is defined as collection of characters that are used to represent some information. It can be a program file, data file or some music file. Data file is defined as combination of interrelated records where record is collection of fields and field is the basic unit of file. E.g. A file related to customer can be defined as: Field Field Field Field Record File Cno Name Address Amount 1 Arjun YNR

Components of a File:  Field: The basic unit of file is called a field. It can be of any type like character, numeric depending upon values to be stored. e.g. in above example name will be of character type, amount is a numeric field. Fields are defined by giving their name, type and maximum value. Record: Combination of fields or combination of data items of different type is called a record. Records can be of fixed length or variable length.

Terms related to a file:  Key Field: Field which is used to identify any record is called a key field.  Primary Key Field: Key field whose value is unique for each record is called primary key field. e.g. CNO in customer file is primary key field. Primary key field can be single or combination of more than one field.  Secondary Key Field: Key field which is not unique for all records is called secondary key field.

Types of Business files: Master file: It is a file which stores the information which is most important for organization. Master file is most important file of any organization. It is of two types ◦ Static master file : It is one which contains information of permanent nature. Contents of this file do not change with the passage of time. e.g. cno, name, add in a customer file defines the contents of static master file. ◦ Dynamic master file : It contains information which changes from time to time according to business activities. e.g. balance of the customer. Ledger is the example of master file in business. Master File Transaction file Library file Backup file

Transaction file: It is one which is of temporary nature. Transaction files are created depending upon organization’s activity cycle. e.g. daybook is created daily but payroll is created after each month. Main aim of transaction file is to modify master file. Moreover it can be used for storing result. Transaction files can be classified as input transaction file, output transaction file, work file. MASTER OUTPUT INPUT WORK

Backup file: It is used to maintain duplicate copy of any data. Backup file is used to store data which can be used in case of accidental loss of data from the main file. This file is maintained for security purpose. But maintaining data increases the cost. Library file: Files which are used only for reference are called library files. e.g. previous year’s ledger in business activity is example of library file.

Different operations on file Creation of file: Creation activity deals with collection and validation of data. Two approaches can be used. In first approach, the space is created and then vales are inserted in the free space. In the second approach space is created as the values are given. Modification/updation of file: Updation involve three main activities:  Insertion of record: New record can be inserted at any free space. Either it can be inserted at the end of file or in between the records by rewriting the file.  Deletion of record: Deletion process is performed just by marking the record to indicate that record is deleted. This space can be used at the time of insertion.

 Modification in existing record: It is a process to change the existing contents of file. It can be performed by using a single file. In this case file to be modified works as input file as well as output file. Records are read, modified and rewritten in the same file. Retrieval of information: This process is related to obtaining output from any file. Retrieval can be performed in the form of enquiry or report. Enquiry: When output is obtained with limited number of records then retrieval is called enquiry. Report generation: In this bulk of information is obtained & output contains large no. of records. Reports are generally obtained in batch mode. Report generation can be performed on either all the records or on records that satisfies the given condition.

File maintenance: This process includes Restructuring: This process includes insertion of some new field or deleting some existing file or changing the characteristics of any field. Reorganization: This process deals with changing organization of the file. A file can be converted from sequential to random or vice versa. Reorganization process is performed to improved efficiency of the processing. In some cases it is automatically performed by the system, in some cases by the user.

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