DATA FILES IN INFORMATION SYSTEM

PRESENTED BY

LT. SONIA MAHINDRU

ASSTT. PROFESSOR IN COMPUTER SCIENCE

DATA FILE

A data file is a computer file which stores data to be used by a computer application or system, including input and output data. A data file usually does not contain instructions or code to be executed (that is, a computer program).

TYPES OF DATA FILES

WORK FILE

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Any file which is required to enable the processing of business data to be carried out is a work file (excluding files required for security or audit purposes).

The designer may or may not have to design such files himself.

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EXAMPLE:WORK FILE

1. Work files used by system software or utilities such as sort/merge processers.

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2. Work files used as intermediate or inter-process files in computer programs at a low level. The design of these files would be better left to the programming team.

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If a file is needed to store Data created by one business process before being used by another business process, then the designer would have to be involved. These files are sometimes referred to as transfer files. The temporary files which hold information for printing also fall into this category. Here the designer needs to specify the record definitions required to produce the correctly formatted to output.

MASTER FILE

Master files are files of a fairly permanent nature, e.g., customer ledger, purchase ledger, inventory pay roll etc. They include some information which is continuously updated by recent transactions. For example, a sales ledger might contain the customer’s names and addresses as well as their current position which is updated periodically.

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The description information in a master file may include such items as product code, description, specifications etc. The normal means of updating a master file is by adding, deleting or amending records in the file.

TYPES OF MASTER FILES

 Static master files (or reference files):

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The business entities that these files describe are at a permanent or semi-permanent nature (e.g., products, suppliers, customers, employees etc.). These are subject to occasional relation.

TYPES OF MASTER FILES

Dynamic master files (or table files):

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The business entities these files describes are of transitory importance to the business (e.g., customer orders, work orders, job tickets, projects, price lists, wage rates) etc.

AUDIT FILE

Audit files are a particular the of transaction file. They play the same role in computerized information systems as the postings in a traditional manual ledger. They enable the auditor to check the correct functioning of the computer procedures, by storing copies of all the transactions which cause the permanent system file to be altered.

AUDIT FILE

For example, in a sales ledger system, the transactions to be recorded might be:

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1. Invoice number, data, cash amount for each invoice raised.

2. Date and amount of cash received.

3. Credit note number, date amount of money credit.

4. Account adjustment, amount of money, cross reference to authorization, adjustment code.

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These files will normally be serial, the records being created at the time of the master file update and accumulated in the sequence of the update, on the audit file.

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TRANSACTION FILE

Transaction files are files in which the data relating to business events is recorded, prior to a further stage of processing and are created from source documents used for recording events or transactions. This further processing may be the use of the transaction data to update master files, or the achieving of the transaction for audit purposes.

After the transaction file is processed, it is usually reinitialized, and further transactions are then recorded in it.

EXAMPLES: TRANSACTION FILE

• Customer’s orders for products (to update an order file)
• Details of price changes for products (to update a product file)
• Details of cash postings in customer accounts (to be held for audit purposes)
• Purchase orders, job cards, invoice dispatch notes etc.

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BACKUP OR SECURITY FILES

These files are taken in order to provide back copies, in case of loss or damage to current versions, and arc copies of currently used master files kept in the computer library as a measure of security.

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In practice, the designer is unlikely to be involved in the detail design of such files, as he would rely either on system security software (e.g., dump/restore utilities; the transaction logging and recovery routines in teleprocessing monitors); or in batch up date system, in holding superseded versions of master files with back copies of transaction files.

THANK YOU