business data processing
TRANSCRIPT
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BUSINESS DATA PROCESSING
How to process a business. IPO cycle. Data into meaningful information. Information as Data. Pros/Cons of the business.
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DATA CAN BE INFORMATION- HOW??
It is required to operate the business-information from customer.-Information regarding the stock available.-To generate the previous invoice.-Current status of the market.
Data is required to control the business -About performance and results
Data originates from the outside demand- Steps to improve the business.
Although these steps may vary according to the need of specific
business.
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VARIOUS BUSINESS SYSTEMS:-
Payroll or wage control system Sales control and accounting system Purchase control and accounting system. Inventory control and accounting system Production control system Cost accounting system
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ROLE OF VARIOUS SYSTEMS:
Contribution to financial and accounting statements.
Actions to be taken to make the business more efficient and profitable.
Make the system automated. Gather req. information to generate various
reports at the door step. Various procedures and problems.
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Staff Recruitment
Wages Accounting
Customer info
Sales Accounting
Purchase accounting
Suppliers order
Sales analysis & Forecasting
Profit/Loss Statement
Balance sheet
Stock control
Production control
Material Costing
Labor Costing
Plant Registration.
Mgmt Acctts
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PAYROLL OR ACCOUNTING SYSTEM:
Mainly employ and remunerate the workforce
Manual, technical and managerial skills Personnel attributes ,capabilities . Terms of employment.
Computation of each employee’s gross earning & salary.
Regarding employment criteria
Computation of employee net payment based on gross earnings.
HRA,TA,DA,PF
Accounting for amounts deducted from earnings.
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SALES CONTROL AND ACCOUNTING SYSTEM: Determine the value of the order to check the
credit rating of the customer Print combined invoice and delivery note. Update the stock record Update the stock record file for the inventory and
issue order notes. Enter details in back order file if the items are out
of stock. Prepare list of the collections of goods in the
inventory. Prepare delivery schedules for the inventory. Prepare and print order analysis reports.
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Customer
InvoicePaymentCustomer
order
Sales representative, Telephone,
Order Sheet
Data Processing System
Productions of Suppliers
Orders Warehouse
Invoice packing
list delivery schedule
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FILES/DATA TO BE MAINTAINED: Stock description file
List all goods supplied by the firm. Details of the min. order quantity. Unit cost/item Discount ( if any)- as per conditions Has to be changed when price alters
Custom or file Customers detail ( name ,code_no, address etc.) Outstanding transactions ( order no, amount involved, date of the
invoice dispatched) Addition of new customers /deletions of old customers. Alteration in their credit limits
Back-order File If delivery has to be made later on particular date Detail of such type of customer
Sales ledger file Details of all the orders which has been dispatched Cost of the items and date on which payment was received. Details of the invoice / modifications if mistake has been made
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FILES/DATA TO BE MAINTAINED:
Exception file Request from customer after getting delivery regarding
Incorrect stock number ( manual record has to be maintained so as to tally the order).
Further queries can be solved .
Suspense file Wrong order delivered . Cheque /cash received only for items received rather than full
order placed. Can be used in future for further queries.
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SALES CONTROL AND ACCOUNTING SYSTEM: No separate delivery /invoice notes are
made• OCR based forms can be generated to
avoid errors and to save time.• Record about company’s / individual sales
rep. efficiency and performance.• Statistics about various customers so that
alterations can be made according to the situations.
• Increasing/decreasing demands for the particular items so as to make the future strategy.
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PURCHASE CONTROL AND ACCOUNTING SYSTEM: Required material,components,tools,equipments and other
material needed by the company. Information at right time/place/price Rules to be followed are: Obtaining quotations of price,
delivery date and quality from prospective suppliers. Placing order with suppliers, monitoring delivery and
chasing overdue orders. Check quality, type of the goods received. Passing information to accounts deptt. for further action
regarding the payments to be made. Checking suppliers invoice and statements before making
the final payments. Accumulating the various statistical data pertaining to the
price ,delivery achievements and quality for the purpose of improving subsequent decisions regarding the placements of purchase orders
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DOCUMENTS ASSOCIATED ARE:
Purchase Order. Goods received notes. Purchase invoices. Remittance advices Cheques. Credit transfers. Purchase analysis. Purchase records.
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MATERIAL MANAGEMENT
Tangible components of the supply chain,
Covers acquisition of spare parts & replacements.
Quality control of purchasing and ordering.
Standards involved in ordering, shipping and warehousing.
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FUNCTIONS RELATED WITH MATERIAL MANAGEMENT: Identification Cataloging Standardization Need determination Scheduling Procurement Inspection Quality control Packaging Storage Inventory control Distribution Disposal Information tech (software availability)
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INVENTORY CONTROL SYSTEM Closely connected in practice with stores control. Monitoring and decision control,operation. Supply and demand. Methods of minimizing the overall cost:
Cost of storage,reordering,capital tied up in stock Stock depreciation & deterioration. Loss of profit due to out-of-stock.
Maintenance of records related to stock control : Stock level,issues,outstanding orders,reorder level Can be applied to raw material,brought-out, made-in-
components, subassemblies, finished and part-finished products, machines and consumable items.
Others factors are: Size & weight of the stock items,stability,identification. Equipment handling,security,packaging,labeling &
space.
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VARIOUS REPORTS REGARDING INVENTORY CONTROL SYSTEM:
Receiving report forms. Requisition and issuance slip form. Warehouse transfer form. Inventory adjustment Form. Transaction Listing. Stock Status Stock management. Historical Price List – Per Item/Vendor Inventory Valuation per classification( Quantity/Value) Non-Moving Inventory classification ( Quality Value). Current 12 months consumption Historical consumption Issue register, excess stock register, under
stock,consumption,category wise consuption,account head wise consumption
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ACCOUNT RECEIVABLE MANAGEMENT SYSTEM:
Calculate sales price and taxes by client, product and order destination.
Allow to add new clients. Prepare invoices for product kits. Insert comments between rows of item
information. Calculates the commissions and produces a
report about commission to be paid. Produces invoices with detailed administration
fees. Group all receipts in one ledger.
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PRODUCTION CONTROL SYSTEM:
Production planning ( how to make ,what to make) Material requirement for each time period. Quantity of components and subassemblies. Amount of equipment, machine, tools needed at
each stage. Amount of each labour category. Loading of each production unit. Progress for each job. Reason for delay. Other type of planning ( according to the need)
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COST ACCOUNTING SYSTEM: Actual/standard costs are compared. Variance.- used for info. & planning Profit variance: Sales variance/cost variance. Sales variance: volume variance (actual/standard) Cost variance: Material / labour. Cost-Production (methods of production/material compromise. Marginal costing, break-even analysis, budgeting Marginal costing- extra cost involved. Break-even analysis-level of profit. Budgeting- controlling analysis by forecasting. Computer power. Raw-data, information Activity and information.
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BUSINESS SYSTEMS
To provide goods & services to society. Business: Exchange of goods, money or services
for mutual benefits. Process data for info. generation. Business Functions
Various internal/external functionsMarketing & SalesFinanceHuman ResourcesProductionPurchasing & StoresGeneral Administration
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BUSINESS SYSTEMS Marketing and sales:
Transfer in ownership of goods and services. To reach the ultimate customer. All activities regarding marketing of the product. Sales – A part of Marketing.
Finance: Funds to run the business. Funds to be converting to the reality. Plans to raise the funds.
Use suitable sources of funds. Funds with min. rate of interest.
Human Resources: Workforce
Managers & subordinates. Contribution of all the members of the company
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BUSINESS SYSTEMS
Production: Creation & services req. to satisfy the customer needs.
Product Planning. Product Development. Production administration. Execution of plans. Polices regarding the production.
Purchasing & Stores: Need material & goods. Req. store to keep goods for later stage. Purchasing and storing are closely related.
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BUSINESS SYSTEMS
General Administration: Direct or Indirect way to control the business. Establish the principal objective of the organization. Prepare plan & policies to achieve the goal. Job to be assign to each department/person. Delegation of powers. Performance evaluation on regular basis.
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SYSTEM LIFE CYCLE
Also called water fall Model
Various stages are:Initial investigation.Feasibility Study.Designing.Implementation.Maintenance
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SYSTEM LIFE CYCLE
Initial investigation: Understand the problem ( Problem def inning phase) Modules. Estimated cost involved. Detail study- Max efforts.
Feasibility Study: Test of the proposed system. Workability. Impact on organization. Effective use of resources. Technical,Economical,Operational feasibility ( computerization) Formal proposal can be presented with:
Details of the problem,suggestions,cost benefit analysis. Recommendations, conclusions
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SYSTEM LIFE CYCLE
Designing: Justification, estimate and impact of system on organization. Methods of data capture. Formats of the output to be used in future. Choose best out of the availability. Discussion with mgmt. regarding cost-benefit analysis and other
objectives also. Security aspects are:
Hardware & software to be used. Inputs(Data entry screens ,default values etc.) Outputs (report screens, screen designs etc.) The user Interface. Testing plan.
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SYSTEM LIFE CYCLE Conversion Plans. Documentation Data Validation. Security Features.
Implementation: Manual to Computerization. New computers instead of old ones. Training,testing,conversions etc.
Maintenance: Corrective & perfective measures for repairing. Changes to be made with changing environment.
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SOFTWARE DEVELOPMENT:
Software required to as per nature and vol. of work.
For better services to the customer.
Own SDC (Software Development center)
Software personals to make suitable software.
Computerization req. training- need software
Training to indivisual.
Problem defining phase.
System analysis. System design mgmt. Programming analysis
and preparation. System
implementation. Maintenance.
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SOFTWARE DEVELOPMENT
Problem defining phase: Identify the problem & available solutions Main role of volume & nature of work. Coordination between data processing employee &
management of the organization.
System Analysis: Data & facts regarding manual procedures. Technical & economical feasibility. Effect of computerization on the organization. Weak points and their solution (available)
System design: How to produce efficient & effective system. Best suitable and favorable design adopted.
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APPLICATIONS OF COMPUTERS
Organize and store many similarly structured pieces of info.
Retrieve a single piece of info. From many stored records.
Print info. Quickly and accurately. Perform complicated mathematical calculations. Perform the same activity almost indefinitely. Facilitate comm. Among individuals,
departments and branches. Link the office to many sources of data available
through larger networks.
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HOW TO IMPROVE Accounts Receivable: If properly organized and
maintained. Requires large hours of posting sales and receipts and especially of preparing statements.
Advertising: Complicated to handle large/Mass data.
Inventory: High volume turnover can cause errors in tracking inventory causes lost sales and in maintences.
Payroll: tough to implement an employee incentive plans.
Planning: tough in manual for planning.
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COMPUTER BUSINESS APPLICATIONS
Financial modeling programs prepare and analyze financial statements.
Spreadsheets and accounting packages Word processing programs. DTP Critical path analysis programs divides large
program into modules Legal programs track cases and tap information
from the data bases. Payroll system File mgmt system.
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REALISTIC EXPECTATION: Don’t expect a computer to clean up a mess
in the office. Don’t install a computer:
If you don’t have the right people to do the job. With the idea that any info. You want is instantly
available. Computer require structured, formal processing that
may produce informal system. To help define the jobs that must be done, but it must
be well defined. To occur like magic, need methodical work. To exactly fit your present methods of completing jobs.
If not willing to listen to new ideas then you will not be able to install computer successfully.
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SELECTING A COMPUTER
Mini computer
Micro computer
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NEED FOR SYSTEM ANALYST
Analyze input, process and, out & flow of data.
Improvement in support of users and functioning of the business.
For poor installation system analyst lends structure to analysis and design of info. System.
Series of processes systematically undertaken to improve the efficiency of the system.
Computerized info. System.
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NEED FOR SYSTEM ANALYST
Works with current and eventual users of info. System.
Latest tech. in organization setting. Users involvement, user move as forefront
as a software development team. More emphasis on the working of the
software users, on performing analysis of their business ,problem & objectives .
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ROLE OF SYSTEM ANALYST
Consultant: with mgmt,users
Supporting expert: existing & proposed system
Agent of change: modification ( if required)
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SYSTEM LIFE CYCLE ( CONTI…..
Preliminary survey Feasibility study. Detailed system study. System analysis. System Design. Coding Testing. Implementation Maintenance
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PRELIMINARY STUDY Brief investigation of the system under consideration.
Preparation of system proposal.: Problem Def, Objectives Terms of reference,Contraints,
Expected benefits in the light of user environment.
System proposal made by the SA,presented to mgmt: accepted or rejected or modifications.
System study Phase passes through the following steps: Prob. Def and project initiation. Background analysis. Inference of findings( system proposal)
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FEASIBILITY STUDY:
Test of the proposed system as per: workability, users req,effective use of
resources ,cost effectiveness Technical,economic,operational and scheduled
feasibility. Main goal is not to solve the problem but to
achieve the scope. Cost and benefits are estimated with greater
accuracy to find ROI( Return on investment)
Resources needed to complete the investigation.
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DETAILED SYSTEM STUDY
Problem and requirements. Pros and cons including new areas of interest. Data and finding in the shape of DFD’s,data
dictionary, logical data structure and miniature specifications
What the new system is accomplished based on users requirements.
Functional hierarchy by the new system and their relationship with the other.
Functional network: for more than one procedure.
List of attributes in the entities.
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SYSTEM ANALYSIS:
Collecting factual data, understand the process involved, identifying the problem, recommending feasibility.
Studying the business process, gathering the operational data, understand the information flow, finding bottlenecks and evolving solutions to overcome the weakness of the system.subdividng the complex process, identification of data store and manual process.
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SYSTEM ANALYSIS:
Finding answers for business process HOW?
Give birth to new efficient system. scope for future growth within organization
constraints.
Iterative process that continues until a preferred and acceptable solution emerges.
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SYSTEM DESIGN
Most crucial phase in the development of the system.
Logical system design is converted to physical system design.
Two stages are: Preliminary or general design. Structured or detailed design.
The tools and the techniques used are: Flowcharts Data Dictionary. Structured English Decision table
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SYSTEM DESIGN Decision tree
Defining the req. system output.Data req. and producing output.Med. And format of files and database.Devising processing methods and use of
software to produce output.Determine the methods of data capture
and data input.Designing input forms, user interface.
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SYSTEM DESIGN
Designing codification schemeDetailed manual procedures.Documentation and design.Data validation.Defining security features.
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CODING
Coding the design into computer understandable language.
To convert pgm. Specifications into computer instructions.
Procedures into controlled specifications. Must be modular in nature, fast
development and future changes (if required)
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TESTING
Before actual implementation –a test run to check the bugs. After codifying –
a test plan should be run on given set of data. Output must match with the expected
results.
Two types of test are:Program Test.System test.
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TESTING Program Test:
Coded, compiled and bought to working nature must be individually tested with the prepared test data.
Bugs noted and debugged. System Test:
After pgm. Test system test is carried out.Complete system is run on actual data.Results are checked and analyzed, errors are
removed and further tested with the expected output.
Finally users are called with their own data.
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IMPLEMENTATION Theory is turned into practice. Major steps are:
ConversionUser Training.Documentation.Hardware and Software req. for implementation
made fully operational initially.Conversions are most important—old data has
to be converted to be operated in new formats of new system.
Database needs to be setup with security and recovery procedures fully defind.
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IMPLEMENTATION After loading training starts. Types of training: How to execute the package, Enter data, Process
data, take reports After training working has to be shifted from
manual to computerized is called
“ Change over”
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IMPLEMENTATION
“ Change over” Direct changeover- Complete replacement (old
to new) Parallel Changeover- ( Both manual & computerized)-
less risky but most expensive ( work doubled).
Pilot run- run on previous periods data for whole or part of the system– results are compared with previous results. Less expensive and risky from parallel changeover.
Build confidence and errors are traced easily without effecting the operations.
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MAINTENANCE
Review of the system from time to time. To eliminate errors during the working phase
and tune the system to any validations in its working environment.
Used for: Knowing full capabilities of the system. Required changes or additional requirements. Studying the performance.
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SOFTWARE DEVELOPMENT
Modifications accordingly (if required) Programming analysis & preparation: New system of app. Specification is turned over to one or
more programmes. Smaller modules. Suitable programming lang. ( according to speed)
System implementation: Testing about 50% for different stages. System is run for shorter time period for testing. If run successfully then implemented.
Maintenance: Documentation is important aspect of maintenance. Rules changes for within or other vendors providing
software.
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SOFTWARE DEVELOPMENT In case of other vendors picked:
Whether software meets requirement completely. Whether updating facility available in software. If party suitable software adopted- modification available. Single/multiuser software available.
Decision making: Support for information system. Problem should be known well in advance. Intelligence- problem exist, design- alternative solution,
choice- pick the best solution. Types of decision:
Programmed & non-programmed. Programmed:- well defind,repetitive,routine decision.
Pre-defind rules or algorithm implemented.
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TYPES OF DECISION:
Non programmed decision: Occasional, no predefined rules, new analysis
every time. Implementation of info. system:
Preparing people for introduction of new system. Developers thinking:
High level of use High level of user satisfaction. Accomplishment of the original objectives. Appropriate nature of use. Institutionalization of the system.
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UNSUCCESSFUL IMPLEMENTATION OF INFORMATION SYSTEM: Reasons are:
Analysis goes wrong. Less time spent in research.
Objective is unclear. Inadequate involvement with the user.
No flexibility is not built in the design.-no further changes can be made.
Not much focus on low level processing, not enough on the information flow.
Mgmt. Can over-specify their requirements.-resulting in unrealistic or excessive demands.
No training to the users. Poor documentation.
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UNSUCCESSFUL IMPLEMENTATION OF INFORMATION SYSTEM:
Badly thought-out conversion. Mgmt. should be involved in design process. Build around the info. Need of the managers
rather than what exactly computer can easily produce.
Inadequate teamwork and lack of professional standard.
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SUCCESSFUL IMPLEMENTATION:
User involvement and user enthusiasm. Training to the user. Proper mgmt. of the system development to
prevent cost overruns/delay etc. Mgmt. support (change in work habits,
organization changes are most likely to be accepted by the staff.)
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Data Processing Concepts
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DATA PROCESSING SYSTEM Process data to the meaningful system.
Process of collection, storage and distribution.Input, Manipulation and editing,Storage and
output. Examples:
Result preparation system.Payroll system.
Input Manipulation (sort of editing) Classifying- Similar items are grouped as a one according
to the code system. Sorting – Rearrangement of data(Asc / Desc) Verifying- accuracy of data. Comparing more than one data item. Recording of same compared data. Summarizing –the final data.
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DATA PROCESSING
Output: final information, reporting, can be used for analysis
Storage: Hard disk, magnetic disk, floppy disk.
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METHOD OF DATA PROCESSING Manual. Semi-Manual. Mechanical. Electronic. Manual:
Processing by individual(through brain) slow, prone to mistakes Vol. of work increase-error increases.
Semi-Manual method: Man and small instruments
(calculators,typewriters,totalling machines) are used. One’s brain and competence.
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METHOD OF DATA PROCESSING:
Mechanical data processing system: Use mechanical devices Speed,accuracy,neatness,control.
Electronic method: Electronic devices are used. Also called EDP. Speed, storage capacity, accuracy,compact,handy. Items used:-Input devices, storage( permanent,
temporary),output.
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APPLICATIONS OF DATA PROCESSING
Sales department: Invoice, return inwards book, sales tax,reciepts vouchers,
debtors collected, debtors outstanding, finished goods inventory
Purchase department: Purchase invoices, creditors paid, creditors to be paid,
inventory position, purchase day book, vendors record
Pay & cash (salary )department: Payroll,payslips,emp. Loan account, bank position, salary
deduction, IT deductions,PF statements
Financial & cost accounting: Receipt & payment account, trial balance, depreciation
account, work in progress, budget figures, job costing.
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CONSTITUENTS OF COMPUTERIZED SYSTEMS:
Hardware Software Procedures Hardware:
Data preparation,input,processing,storage ,printing. Software:
System software. Operating system software. Language software.
Application software.Req. for performing various activities in institution.
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ADVANTAGES OF EDP Speed Accuracy Storage capacity Diligence-tiredness Cost reduction. Space requirement. Versatility-transfer data internally, functions of
comparisons,arithmatic operations, exchange info with outside world.
Automation Diligence. Volume of data. MIS Flexibility.
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DISADVANTAGES OF EDP:
Installation cost. Stand by arrangements (UPS),air-conditioners. New hardware and software Efficient and knowledgeable persons. Disk failure/corrupted. Lack of judgment of computer.
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ON-LINE PROCESSING: Remains in direct control of CPU. Processes data immediately. Used to overcome batch processing.
E.g. railways, airline reservation system,banking,stock-exchange, foreign-exchange mgmt,work progress in plants, stock control
Data stored in secondary storage. Validation is checked before storage.
Validation data is processed & update the master file immediately.
Updated hardware/software req. High storage capacity. Transaction,inquiry,response. Record lock facility is available.
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BATCH-PROCESSING SYSTEM:
No. of similar transactions collected/grouped in batches and processed at once without any interruption.
Results obtained periodically. e.g. accounting system, payroll system.
Cost effective. Data is accessed sequentially.
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BATCH-PROCESSING SYSTEM:
Advantages: Handle large amount
of data . Output very quickly
while printing. presence of user is not
compulsory while processing.
Suits for lengthy jobs.
Disadvanges: Take longer time
duration in processing. Since master file is
updated so it will take time for final updation.
Results are often delayed.
No direct access to system.
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COMPARISONS:
Batch processing: Files are on-line while
processing. User has no direct access
to the system. Data is collected and
processes in batches. Master file is updated
after the last record is completed.
Suitable for high volume transactions.
On-line processing: Files are always on-line. User has direct access to
the system. Data is processed as soon
as transaction takes place.
Master file is updated as soon as transaction takes place.
Suitable foe reservation and business control system.
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File organization
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DATA ORGANIZATION
Organized before processing Hierarchical Approach is recommended. Various terms are: Data Item Field Record File
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DATABASE
Collection of related files: Variable & fixed length records
Variable length records:
Record A Record B Record C Record D Record D
120 bytes 120 bytes 120 bytes 120 bytes 120 bytes
Record A Record b Record C Record D Record E
120 bytes 150 bytes 200 bytes 500 bytes 270 bytes
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DATA BASE
Logical v/s Physical records
Logical Physical IBG
R1 R2 R3 IBG R4 R5 IBG R6 R7 R8
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FILE ORGANIZATION:
Data and information Data:
Collection of well defined numbers,informations and facts.
Data is meaningful fact. E.g. 4532432 not mean anything, related to any item
means anything. Information:
Processes data on which decisions and actions are based.
Organized and classified data to provide the meaningful information to receiver.
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DATA AND INFORMATION:
PROCESS
DATA
OUTPUTINPUT
INFO
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CHARACTERSTICS OF INFORMATION:
Accuracy: should be accurate Form: in the useful form to the user
and understandable. Relevance: information gains in value if
relevant. Perfect timing: provide within time. Completeness: complete when needed. Purpose: Info. should have purpose when
provided. Reliability: should be reliable. Validity: closeness of info to the purpose.
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DATA FIELDS
Individual data items in a record. Size of the field. Cumulative size( sum of all the fields) Records in the file with same structure Records in the file with variable structure Diff. between same and variable field record.
Header Item Item Item Item Item
Header Item Item Item
Header Item Item Item item
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CONCEPT OF DATA FIELD:
Individual data items are called data field. Primary field:
Uniquely identify the record/column Secondary field:
Second to the primary field. Data collection:
Initial stage (internal/external)Internal: predefined formats.e.g. loan cases
External:depend upon the survey(availability)
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DATA VERIFICATION & INTEGRITY:
Data editing: Addition of relevant records and deletion of
irrelevant records. Generally done by the supervisor, not by DEO
Data checking: Accuracy checks to remove the irrelevant data. Relevant messages regarding data entry screens.
Conditional checks can be applied.
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DATA BANK
Data Bank Keeping points in consideration. Random methods not followed.
Little deviation accepted Data should be bulky rather than small volume.
Some source from where derived. Interaction with events and audience. E.g . Employee database/catalogue of the university
library.
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DATA VERIFICATION & INTEGRITY: Data verification:
Whether up to the requirements or not. Apply check controls for verification.
Integrity: Data contained in the table or file accurate or consistent.
Data preparation: Preparation of database for info. Generation. Depends upon:
Present trends in the market Available products. Price range of the product. Target consumer. Deviation in the taste of the customer. Potential area for marketing of the product.
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FILE CONCEPTS:
Bit,Byte,fields,record,file. Biodata (file name)
Name Age Sex address Qualification
Raman 21 M Una Bsc
Suresh 22 M Una BA
Simpy 23 M Una B.Com
Rekha 21 F Una BBA
Monika 21 F Una BCA
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FILE CHARACTERISTICS
Responsibility of system software known as IOCS ( Input-output control system)
Record Size- size of record in a tape/ chosen by the programmer
Block size- consecutive records .No. of records is called “Blocking factor”
Buffers-I/o operations independent of CPU known as data channel.
Label records/Disk dictionary-file header stores most imp. Info. Called file title. IOCS maintains data dictionary.
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TYPES OF FILES: Master file Transaction file Backup file(dump file) Report file Archival file Transfer file Master file:
Primary file, permanent nature, records kept for long terms.
E.g. Biodata of emp, banking system Two categories:
Reference master file-records unlikely to change in nature. Dynamic master file-frequently updated records.e.g routine
business activities, reservation chart.
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TYPES OF FILES:
Transaction file: Also called movement or input file. For daily updation of records( e.g. sale/purchase) Used to update the master file. Temporary in nature. Not of any use after updating the master file.
Backup file: Duplicate copy of master/transaction file. Used for security.
Report file: Also called Output file. E.g. water, electricity bills, monthly salary of emp.
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TYPES OF FILES:
Archival file: Information regarding the past events of the firm. Used for info. and conclusions.
Transfer file: Used to carry data regarding an event
(business/production transaction) Used to serve input to another process to create or
update another file. Used for sorting file. Sorted file can also be used to update master file.
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FILE ORGANIZATION:
Serial files Sequential files Index sequential file. Random/direct access file. Serial file:
Records are stored one after another serially. No order of arrangements E.g. magnetic tape.
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FILE ORGANIZATION:
Sequential file: Files are arranged as serial. Data is asc/desc. Used sequential search. Master files/batch processing. Updation (add/delete)takes lot of time.
Advantages: Files are simple, easy to design. If processing rate is high then system is economical and
efficient. Input medium is less expensive. Record key is required to locate the record. Can be created on any design.
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FILE ORGANIZATION:
Disadvantages: When activity rate is slow updation is time
consuming. Only disk file are to be updated. Add/del is tedious job.
Relative files:Each record is identified by its original position within the file. Can be accessed randomly as well as seq.. For sequential access simple execute READ and WRITE.
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For random access you must define the data item as a relative key and then specify, in the data item, the ordinal number of the record you want to READ and WRITE. Indexed File: Each record include a primary key to distinguish one
record from another Primary key is unique. Can be accessed randomly by entering value of the
records primary key Can be accessed sequentially Also contain alternative key( one or more additional
keys)- need not to be unique.
5
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Index sequential file: Created on magnetic disk. Retrieved by direct/sequential method.
Advantages: Updation simple,recors linked between two files,
quick access to the file is possible, economical and efficient.
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FILE ORGANIZATION:
Disadvantages: Storage space is not fully utilized. Records can be linked between two files. Expensive hardware/software is needed. Add/delete is tedious as it effects the index file. Only stored on direct access storage devices like
disks. Random/direct access method:
Direct access to the record without reading the previous number.
Use index number.
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FILE ORGANIZATION:
Advantages: Immediate updation is possible in a lesser time. Job is efficient as time consuming is less. Immediate access to the file is possible.
Disadvantages: Expensive-hardware is req. Less efficient in terms of utilizing storage space. Not well suited for batch processing. Access on magnetic disk, tape if useless.
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FILE OPERATION:
Accusing of records:- No updation is done ,only records are accessed. File enquiry: if there is any dispute between party and the
company. File updation: records are updated in the master file. File maintenance: addition/deletion/updation of records.
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FILE PROCESSING IN CASE OF SEQ/SERIAL ACCESS DEVICES: Updation:
Magnetic tape as storage media. It is not possible to add records after the record is
read. Involves the creation of new master file. Should be in seq. file.(e.g. cassette)
Maintenance: Add records to correct seq.
Referencing: Searching/ref a record, each record has to be go
through. Enquiring:
Used for particular enquiry.
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FILE PROCESSING ON DIRECT ACCESS STORAGE MEDIA:
Two ways are there: When data is organized in serial manner. When data is organized in non-serial manner.
Serial manner: Similar to record stored on tape. True direct access can not be applied as data is on
tape. Only possibility is binary search.
Non-serial: Possible to add record at the place of reading. Original master file is updated by the updated
master file.
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FILE MAINTENANCE:
File maintenance: Not possible to store the Updated record at the same
place after updation. Sufficient space should be there.
Indexing: Record keys are listed with the app. Key address.
Address generation: Mathematical formulae can be applied to solve the
problem. File activity ratio:
No. of record accessed/total no. of record
102
ADDRESSING OF RECORDS: Direct access:
Primary keys are used to access the records. Records are seek & read in one pass. Processing time is min. E.g. result system ( primary key as roll no.) Disadvantage:
Wastage of storage space req. for every address. Indirect access:
Address is generated by the mechanism hashing scheme. Transforms the key space to the address space of the records. Diff. routines are used and best is used after analysis. Corresponding to a record a unique address is generated. In this address record is to be resided. If record key generates the same address then collision occurs. Otherwise synonyms occurs.
103
METHODS OF DEVELOPING HASHING SCHEME:
Method of division: Each key is divided by a suitable no, quotient is used for
addressing the records in a direct file. Method of remainder:
Each key is divided by a suitable no, remainder is used for addressing the records in a direct file.
Method of truncation: Uses division method, uses power of 10 for division. E.g. 8-digiy key is assigned to 3-digit address.
5524682 results in 682. Method of folding:
Extracting of digits by folding the key address upon itself. 613083=613+083=696
Method of extraction: Suitable group of digits can be extracted from the key field.
552468261- 3 digits can be selected from the middle to give the result, also 2,5,8 digit can be used to give the address as 566
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SEARCHING:-
Binary search:
N records
n/2 recordsFirst half Second half
n/2 first records
N1/2 n1/2
105
INDEX SEQ. ACCESS METHOD: Original file is kept in desired sequence. On entry for every block of record is made.
e.g. suppose 40 records in each block & n is no of total blocks, then there will be n/40 entries in the index file, if n=32000 then
INDEX FILE=TOTAL RECORDS/BLOCK SIZE
File labels:header label and trailer label.
Header labels:-file name, date written, purge data( date on which data deleted)
Trailer labels:-Last record in the file, contain all info of the header file. also record of record count
Header label trailer label
106
COBOL
High level language.Used specially in data files.File oriented language.
MF COBOLRM COBOLMS COBOLCICS COBOL
107
ELEMENTS OF COBOL:
Valid characters Letters,digits,characters,special characters.
Punctuation characters. Grammatical rules as in English language
E.g. ( ) , . ; + _ * / : Semicolon or comma must not proceeded by a space. At least one space between two successive words. Command can be used as a separator between two
statements. Relational characters must be preceded by a space also
followed by a space.
COBOL Characters. Reserved words, user define words.
108
ELEMENTS OF COBOL:
Reserved words ADD,READ,OPEN,SUBTRACT,CLOSE,ZERO, SELECT,WRITE,DIVIDE,SPACE,MOVE,PICTURE.
User define words. Literals/Constants.
Literals is a constant( integer or real) Numeric literals. Non numeric literals. Figurative constants
109
LITERALS Numeric literals:
At least have one digit but not more than 18 digits. Characters 0-9 can be used. No blank is allowed between sign and first
characters. It may have sign + of – If sign is omitted it is treated as positive. Decimal point is allowed in literals. It may appear anywhere except as last character.
E.g 26, -8,333, 0.5 are valid 22. ,+ 89, 21,564 are invalid
110
LITERALS Non numeric literals:
String of COBOL characters enclosed within quotation marks. E.g. “Marks”
Rules; Max 120 characters in strings. Start and end with “ ”. Any characters any be placed between “ ”.Figurative constants:Special type of literal in COBOL.
e.g. ZERO,ZEROS,ZEROESSPACE,SPACES,LOW-VALUEHIGH-VALUESQUOTE,QUOTESALL
MOVE ZERO(ZEROS) TO WORK.
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DIVISIONS OF COBOL PROGRAM IDENTIFICATION DIVISION. ENVIRONMENT DIVISION. DATA DIVISION. PROCEDURE DIVISION. IDENTIFICATION DIVISION:
First division. Simplest division. Must be coded in every COBOL programe. Main purpose is to identify the source pgm. And related
info. No. of paragraphs without sections. Division header is must and followed by ( . )
E.g. PROGRAM-ID. CALC Other lines are optional.
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IDENTIFICATION DIVISION
IDENTIFICATION DIVISION 1 PROGRAME-ID. Program-name 2 [ AUTHOR . [Comment entry] ] 3 [ INSTALLATION. [Comment entry] ] 4 [ DATE –WRITTEN. [ Comment entry] ] 5 [ DATE-COMPILED. [ Comment entry] ] 6 [ SECURITY. [comment entry] ] 7
If entry is put in [ ] then it is optional and may be omitted. 4- name at which source pgm. was written. 5- when pgm. was written. 6- when was compliled 7- security level attached to the pgm by programmer. Must begin in area A (column 8-11) Coding of comment section area is in area B (column 12-72)
113
ENVIRONMENT DIVISION:
Machine dependent section . Req. in every program and come after identification
division. To specify the configuration of the computer used to
compile the source pgm. and to run object pgm. Info. Related to i/o Hardware,characterstics,control
tech. OS characteristics. Division has two sections:
CONFIGURATION SECTION. INPUT-OUTPUT SECTION
114
ENVIRONMENT DIVISION: CONFIGURATION SECTION: Contain three paragraphs: SOURCE –COMPUTER.-computer used for
compilation.e.g IBM-PC OBJECT –COMPUTER- on which it is to be executed. SPECIAL-NAMES PARAGRAPH Assign user defined name. Used to change editing characters.
e.g POINT IS COMMA. PRINTER IS LP
If any of the above paragraphs are included in pgm,then header must be entered.
1st and 2nd are for documentation purpose and serves as comments.
115
Relation in three division
The i/o device that will be used to read or write will be define in ENVIRONMENT DIVISION.
DATA DIVISION specify the characteristics and structure of the data within the files.
PROCEDURE DIVISION specify the read and write statements for using these files.
116
INPUT OUTPUT SECTION:
Must specify if user is using any i/o within a program for i/o purpose.
This is the header area. Must be start in area A. If data files are not required then this section is
not required as COBOL processes on files so this is the must part. concerned with i/o devices.
This section has two parts: FILE-CONTROL paragraph. I-O-CONTROL paragraph
117
INPUT OUTPUT SECTION:
FILE-CONTROL paragraph: Names the files that are to be processed and
associate files into specific i/o devices. Example:
SELECT BILL-FILE ASSIGN TO DISK SELECT BILL-LIST ASSIGN TO PRINTER.
Assign clause does the association between file and devices. there are separate clauses for seq,direct,index-seq. files.
Some other clauses are: ORGANISATION IS SEQUENTIAL ACCESS MODE IS SEQUENTIAL.
118
I-O-CONTROL paragraph: Special control req. to control the exe. Of the
program. SAME AREA clause defines that two or more
files uses the same memory.
119
Example: ENVIRONMENT DIVISION. CONFIGURATION SECTION. SOURCE –COMPUTER. OBJECT-COMPUTER IBM-PC SPECIAL –NAMES.
PRINTER IS LP. CO1 IS CHANNEL-1. CURRENCY IS “RS”
INPUT-OUTPUT SECTION. FILE-CONTROL.
SELECT OLD FILE ASSIGN TO DISK. SELECT TRANS-FILE ASSIGN TO FLOPPY. SELECT REPO-FILE ASSIGN TO PRINTER.
I-O CONTROL. SAME AREA FOR OLD-FILE. TRANS-FILE. REPO-FILE.
120
DATA - DIVISION Complex of all the division in COBOL. Define all the variables. Data that the program accept as input to manipulate , to create
output. Three categories are:
Data in the files that is as input and output. Data in the work areas on computers. Constant data that is to be used by the program.
SOME TERMS ARE: Item
Elementary item. Group item. Independent item.
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DATA DESCRIPTION ENTERIES : PICTURE CLAUSE
General characteristics of an elementary data item CLASS
Three class-numeric, non numeric, alphanumeric SIGN
Signed/unsigned-implicitly considered as unsigned and during exe. Treated as positive
POINTER LOCATION Position of decimal point in case of numeric data, if not specified
then immediately after the rightmost digit SIZE
No of characters /digits req. to store the data. CODE CHARACTER
Diff. codes are used to store the various kind of data.
122
DATA DESCRIPTION ENTERIES :
PICTURE PIC –Both are the characters tics. Code characters:
9-indicates the corresponding character position contains a numerals.X-any allowable characters from the COBOL character set.A-contains only letter or space characterP-position of the assumed decimal point when point lies outside the data item.S-data item is signed.
123
Exp. Of code characters:
PICTURE IS S999V999 PIC IS PPP999 PIC XXXXXX OR X(6) VALUE CLAUSE:-
Value is literal Exp:- VALUE IS 3.5. VALUE IS “MY DATA”. VALUE ZERO.
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03 NUMBER-ONE PIC s9(3)v99 value -3.25
Exp:- 01 source-data value is “236752”.
02 data-1 pic 9(2) 24 02 data-2 pic 9(3) 375 02 data-3 pic 9(1) 2
125
Data Division Header
Req. part of every COBOL Program. Start with the header DATA DIVISION It contains three sections: FILE SECTION WORKING STORAGE SECTION FILE SECTION
Described the data of the files that is described in File-Control paragraph on Environment Division.
WORKING STORAGE SECTION Data used in program that is not part of the
input and output.
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File section
File description entry followed by one or more record description, must start with level indicator. File name should be same as desc.Descrived in environment section.
Exp
FD file-name LABEL records are standard/omitted
Standard means specified for disk filesOmitted means for card reader/printer files.
127
Example:
Card column date field type 1-5 salesman-no num 11-15 quantity numeric 21-3.0 unit-price numeric ( 2
decimal places)
31-40 amount numeric ( 2 decimal
places)
Let the file name be card-file The entries in the file section should be
128
Example:
FD CARD-FILE. 01 CARD-RECORDS
02 SALESMAN-NO PIC 9(5) 02 FILLER PIC(X(5) 02 QUANTITY PIC 9(5) 02 FILLER PIC(X(5) 02 UNIT-PRICE PIC9(8)V99 02 AMOUNT PIN 9(8)V99 02 FILLER PIC(X(40)
Filler can be used for those fields on the cards which do not contain any data such are described as alphanumeric data.
129
Working-storage section:
Can be group items containing all its subdivisions. There may be elementary data item which do not belong to this group such are defined by a special no 77. it must begin in area A.
Example:
130
Example:
Working-storage section 77 alpha-string pic x(20) 77 data-N pic 9(3) value zero 01 date
05 day pic 99 05 filler pic X value”/” 05 month pic 99 05 filler pic X value “/” 05 year pic 99 01 Inter-string pic x(20)
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Editing:
Print the numeric data suppressing the leading zeros.
Edit characters for numeric data are: Z,*,$,-,+,CR,DB,., , ,B,O,/ Z(zero suppression)-same as 0-9 except the
leading zeros in the source data. Z can not appear to the right of 9. it may also be noted that after the decimal point either the digit position are indicated by all Z or none at all.
132
Example:
ZZ999 04678 B4678 ZZ999 00052 BB52 ZZ999 1^68 BB0001 ZZZV99 38^4 B3840 ZZZV99 0^65 BBB65 ZZZZVZZ 0665 BBBB05 ZZZZVZZ 0^ BBBBBBB
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* (ASTERISK) SIMILER TO z EXCEPT THE LEADING ZEROS ARE REPLACED BY *
**999 04678 *4678 **999 00052 **052 **999 1^68 **001
$ (CURRENCY SIGN) APPEARS AT THE RIGHTMOST LEFTMOST POSITION. $
SIGN IS INSERTED.
$99999 985 $00985 $ZZ999 985 $BB985 $**999 985 $**985
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- (MINUS SIGN)
Appear either at right or left place -9999 -382 -0382 9999- -382 0382- -zzzv99 -46^52 -b4652 -zzzv99 46^52 bb4652
+ (plus sign) Similar to – (minus sign)
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CR and DB
Can appear only at rightmost position ,similar to minus sign edit 9999cr -4562 4562cr 9999cr 4562 4562bb Zzzcr -42 b42cr Zzz9v99db -152^25 b15225db Zzz9v99db 152^25 b15225bb
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.(period/decimal point) 9999.99 324^25 0324.52 zzzz,.zz 0 bbbbbb $zzz9.99 0285 $b285.00 ,(comma) Zz,z9.99 123^45 b1,23,45
137
B(blank insertion) Insert a space character 99B99B99 1510182 15b01b82 0(zero insertion) 0 will be inserted instead of blank. 9900 12 1200 09990 456 04560
138
/(slash insertion) 99/99/99 150681 15/06/81 999/999/99 3245 000/032/45
Blank when zero: Will set entire data to blanks if its value equal to
zero. * can not be used when blank when zero is specified. it is ignored by the compiler.
Example:- Zzz.99 blank when zero 2^5 bb2.50 999.99 blank when zero 0 bbbbbb Zzz.99 blank when zero 0 bbbbbb
139
Floating insertion:
Appears in multiples of the left hand side of the picture.
$$$$9.99 235^25 b$235.25 $$$$9.99 342 b$342.00 ++++.99 -475^25 -475.25 ++++.99 45 b+45.00 ----.99 -3^ $$-3.50 ----.99 -3^5 $$-3.50
140
Special –name paragraph If currency symbol other than $ is req. to for editing then
symbol may be edited in SPECIAL-NAMES paragraph of the ENVIRONMENT DIVISION.This character may not be adigit or letter A to D,L<P,R,S,V,X,Z or special character blank *,-,.( ) +’ ‘ = / etc.
SPECIAL-NAME. CURRENCY SIGN IS “character” DECIMAL POINT IS COMMA.
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CLASS AND CATEGORIES OF DATA
Alphabetic,Nummeric,numeric edited, Alphanumeric and alphanumeric edited.
A B 9 P S V 9 P V and at least one of the editing symbol
like B / Z O + - * CR DB X 9 and must contain 9 and A X 9,A,B,O and at least 0 or /
142
Levels of data item: Elementary and Group Elementary Level class category Elementary alphabetic alphabetic Numeric numeric Alphanumeric numeric edited Alphanumeric Alphanumeric edited Group
Alphanumeric elementary data within the group
143
Clauses:
Blank Justified Sychronized Rename Redefine Usage Value occours
144
Blank Clauses:
Blank: The screen description entry has various clauses
in ACCEPT and DISPLAY clauses. Level-number [screen name]
[blank screen] [location-spec] [BLANK LINE] [BELL] Underline Reverse video field name blank when zero Highlight justified right Blink just [auto,secure,required,full]
145
Justified: Used to justify (reverse) the standard left hand alignment
of the alphanumeric/alphabetic data. JUSTIFIED RIGHT JUST SYNCHRONISED CLAUSE:
Allocates contiguous storage space to data items. Comp-1 allocates 4 bytes. First byte starts immediately. After previous data. Data may not start with the word boundary. This difficulty is solved by SYCHRINIZED.
Syntax: SYCHRONIZED SYNC
146
Example: 01 SAMPLE-DATA
02 DATA-1 PIC X(10) 02 DATA-2 PIC 9(5) COMP SYNC 02 DATA-3PIC S9(5)V99 COMP-3
Rename clause:Regrouping of elementary item in record.Syntax:66 data-name-1 RENAMES Data-name-2 THRU Data-name-3
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Example: 01 SALARY-REC 03 FIXED-SALARY 05 BASIC-SALARY PIC 9(7)V99 05 DA PIC 9(7)V99 03 SPECIAL-PAY 05 HRA PIC 9(4)V99 5 ALLOWANCE PIC 9(3)V99 03 DEDUCTIONS 05 PF-DEDUCTION PIC 9(3)V99 05 INCOME-TAX PIC 9(4)VPP 05 OTHER-DEDUCTION PIC 9(3)V99 66 SALARY-OTHER-THAN-BASIC RENAMES DA
THRU ALLOWANCE 66 IT-AND-PF-DEDUCTIONS RENAMES PF-DEDUCTIONS THRU INCOME-TAX
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Rules for rename clause:
Written only after the last record entry. Used only after the level number 66. Data name-2 and data-name-3 can be names of
elementary data items but no case they be the members of 01,66,77,88
Data-name should not be used as qualifier. Data-name-2 as well as data-name-3 can not
have OCCOURS clauses. If data-name -3 be mentioned then it should be
follow data-name-2
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Redefine clause: Use for the purpose allows the said area to be referred by
more than one data name with different size and picture. Syntax: Level number data-name-1 REDEFINES data-name-2 Example:
01 SALARY-REC 02 SALES-TYPE PIC 9 02 SALES-BY-COPIES. 03 QUANTITY PIC 9(4) 03 COPIES-PRICE PIC 9(7)VPP 02 TOTAL-SALES REDEFINES SALES-BY-
COPIES. 03 BILL-AMOUNT PIC 9(9)VPP 03 FILLER PIC X(2)
150
Rules for redefine clause:
Level number of data name 1 and data name 2 are identical.
Both should be of same size except when redefine clause used for 01 level.
Multiple redefine clause can be used. Entries of new description can not have value
clause. Redefine clause should not be used for records
(01 level) Redefine clause can not be used for level no. 66
and 88.
151
Working storage section:
Used to provide the heading for reports. Contain entries for independent (non-contiguous)
items and record description entries.2nd are not part of external files and are developed and processed internally.
1st have no hierarchical relation with each others and defined with level no 77.
2nd are data items and have definite relationship with each other.
Record are formed according to to the rules of record description.
152
Working-storage section:
It begin with a header followed by a period. Working-storage section
77 non-contiguous data items 01 record description entries.
Record items: Basic components of COBOL. Identified by having a data name with 01 level
number. Level will be in area A and data name in area B. May be elementary data item or group item.
153
Working-storage section:
Example:
01 P-REC 03 MONTH-CODE PIC X(^) 03 MONTH-DAY
05 MONTH-DATE PIC 99 05 MONTH-MONTH PIC XXX 05 MONTH-YR PIC 99 03 MONTH-RED PIC 9(6)
154
Working-storage section: FILLER CLAUSE:
05 FILLER PIC X(12) Filler is mostly used in records for printing purpose to leave
blanks between two fields.Example:01 PRINT-REC
05 EMP-ID PIC X(5)05 FILLER PIC X(5)05 SALARY-DATE PIC X9905 FILLER PIC XX05 SALARY-MONTH PIC XXXIF EMP-CODE IS T1121SALARY-DATE IS 10SALARY-MONTH IS AUG
OUTPUT WITH FILER CLAUSE WILL BET1121 10 AUG
OUTPUT WITHOUT FILLER CLAUSE IS T112110AUG
155
CATEGORIES OF DATA:
Alphabetic Numeric Alphanumeric Alphanumeric edited Numeric edited. Alphabetic 03 namepic z(30) Numeric: 05 pay pic 9999 Alphanumeric: 05 address pic x(75)
156
CATEGORIES OF DATA:
Numeric items: Are described by giving 9 in the PIC clause. S represents the operational sign. V and S are sizes os an item.
157
Usage clause: Used to specify the form in which numeric data is
stored in the computer. this clause appears in data description or record description eneteries in the FILE-SECTION and WORKING-STORAGE SECTION.
Format is: DISPLAY COMPUTATIONAL OR COMP USAGE [IS] COMPUTATIONAL-1 OR COMP-1 COMPUTATIONAL-2 OR COMP-2 COMPUTATIONAL-3 OR COMP-3 INDEX
158
Usage clause: DISPLAY: It indicates that one character can be stored in
each byte of an item. if usage is display the data item need not to be numeric valid even for alphanumeric. it is the default clause.
COMPUTATIONAL: It must be numeric. specified for numeric data
items. The amount of storage to be occupied by the binary data item depends on the no. of digits in its PIC.
1-4 pic 2 bytes 5-9 pic 4 bytes 10-18 8 bytes.
159
Usage clause: 05 UNITS PIC S9(8) USAGE COMP OR 05 UNITS PIC S9(8) COMP Another example: 05 PAYMENT COMP
10 COMP PIC S9(3)V99 10COMP PIC S9(3)V99 Comp-1 items are 4 bytes in length Comp-2 items are 8 bytes in length Comp-3 items are stored in packed decimal
format (2 digits per byte) with low order for bits of the right bit bytes containing the operational sign. increases the effectiveness of the programe.saves time.
If the data is for simple i/o purposes. DISPLAY clause should be used in default.
160
Value clause: Used to initialize the data item before the
program execution starts.. Allowed in working-storage section. Does not allow this clause in file section. It is permitted in the description of elementary
items and group items. Format is Value is literal 77 tax-rate pic 9v99 value 0.25 (numeric) 77 sex-code pic x value ‘M’ non-numeric 77 marks pic 999 value zero 77 qualification pic 999 value zero
161
Occurs clause: it becomes quite often necassry to handle a group consisting of
similer items . Such a group is called table. Example: Suppose ten diff. items of discount rate 01 DISCOUNT 02 DISCOUNT-1 PIC 99 02 DISCOUNT-12PIC 99 02 DISCOUNT-3 PIC 99 02 DISCOUNT-4 PIC 99 02 DISCOUNT-5 PIC 99 02 DISCOUNT-6 PIC 99 02 DISCOUNT-7 PIC 99 02 DISCOUNT-8 PIC 99 02 DISCOUNT-9 PIC 99 THIS CAN BE REWRITTEN AS 01 DISCOUNT
02 DISCOUNT PIC 99 OCCOUR 8 TIMES.
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Rules for occur clause. It can not be a negative number. Can be specified for an elementary item or a group item. Can not be specified for level no 01,66,77,88 When data item is define with occur clause then such data
name and its subordinate items ( if any) can not be referred in PROCEDURE DIVISION.
The range of value is from 1 to highest possible value of the subscript.
The subscript should be enclosed in set of parenthesis. When array is defined with occur clause ,the value clause
can not be specified for that particular item. Can not appear in the same data description entry which
contain an OCCUR clause but the REDEFINE can appear for a group item whose subordinate items are define with the OCCUR clause.
Can appear in the data description entry in any order.
163
Procedure division Contains the statements which specify the operations to be
performed by the comp. it always start with a COBOL verb.
ADD ALLOWANCE TO BASIC –PAY. IF TOTAL-PAY IS GREATER THAN 1000 GO TO PARA-TAX-
CALCULATION. A comma or semicolon may be used to delimit statements followed
by space. Sentences can be grouped to form the paragraph and paragraphs
can be used to form sections. It can be headed by the name. section names are user defined.
Operations required to process the data are as under:Input/outputData manipulation.Arithmetic calculations.Sequence control.
164
Procedure division
EX: MOVE ’akshay’ to name Accept no Add DA, basic giving gross A sentence can be composed of more than one
statements. Add a to b Move salary to gross Subtract deductions from gross. PARAGRAPH IS MADE OF MORE THAN ONE
STATEMENT.
165
INSERT-REC MOVE IN-REC TO OUT-REC WRITE OUT-REC READ IN-FILE AT END STOP. A section is the largest division of the
procedure division. It consists of section header and one or more
paragraph one after the another. COBOL verbs:
procedure division are prescribed by the use of COBOL verbs they take place either at compilation/execution time.
166
CLASSIFICATION OF VERBS:
INPUT/OUTPUT VERBS: ACCEPT,DISPLAY,OPEN,CLOSE,READ,WRITE.
ARITHMATIC VERBS: ADD,SUBTRACT,MULTIPLY,DIVIDE,COMPUTE.
DATA MANIPULATION VERBS: MOVE,INSPECT,EXAMINE,STRING,UPSTRING.
SEQUENCE CONTROL VERBS: GOTO,PERFORM,IF,STOP,RETURN.
COMPILER DIRECTIVE VERBS: COPY,ENTER,USE,EXIT
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INPUT/OUTPUT VERBS: ACCEPT STATEMENT: Although COBOL is used to handle large amount of data,
but sometimes it is necessary to read very important data or initial data from terminal. For that purpose ACCEPT clause is used.
Format: ACCEPT identifier FROM mnemonic-name ACCEPT DARATE MORE: ACCEPT DARATE FROM CDR
WHERE CDR IS THE SPECIAL NAME DEFINE IN Environ. Div.
ACCEPT CUR-DATE FROM DATE OS places the system date into the CUR-DATE.
168
INPUT/OUTPUT VERBS:
DISPLAY CLAUSE: Used for output Display “good-morning” Display abc
Display value stored in abc on screen Display “ my name is “ abc.
MOVE VERB: Move the data from one area of storage to one or
more storage area. MOVE A TO B MOVE AA TO AB. MOVE N1 TO N2
169
INPUT/OUTPUT VERBS:
Move: Move numeric to numeric:
Data is aligned on the assumed decimal point in the destination area.
Digit on the either end that do not fit are omitted. Numeric part on right and decimal part on left. If receiving data is large then sending data blank
all the left positions are filled with zeros.
170
Numeric to alphanumeric: when source is numeric and receiver is
alphanumeric Move num to anum
Pic 999 pic x(5) 123 123 bc
Move 125.7 to dollars Dollars pic 9(4)v99 012370
Move zeros to amount Amount pic 999v99 00000
171
Alphanumeric to alphanumeric Move code-1 to code-2 Pic x(5) pic x(5) Pc 001 pc001
Move group items: 03 m-item 05 m1 pic 999 05 m2 pic x(3) 05 m3 pic 99v99 05 m4 pic a(4)
172
INPUT/OUTPUT VERBS: Another group is
05 p-item 07 p1 pic x(7) 07 p2 pic 9(7)
M1 has 4 data items and p-item has 2 data items and both are 14 bytes.
Fact move is not possible but group move is possible
Move m-item to p-item 03 m-item pic x(14) 03 p-item picx(14)
It is not necessary that both items should have the same length .they may be larger or smaller
173
INPUT/OUTPUT VERBS:
Perform statement: Used to execute a group of consecutive statements
written elsewhere in the program. Temporary departure from the normal sequential
execution. After ex. Of the req. statement control implicitly
returns to the next statement following the PERFORM statement.
possible for specified number of times. Syntax: PERFORM proc-name-1 THROUGH proc-name-2 PERFORM COMPUTE-INCOME-TAX PERFORM START-COMPUTATION THRU END-COMPUTAION
174
RULES FOR RANGE OF A PERFORM STATEMENT:
a GOTO statement is allowed within the range of perform statement.
There is no restriction as to which should be the last statement of a range. When the if sentence is used at the end of a range the next sentence refers to the return mechanism.
The use of perform statement within the range of another perform statement is possible.
The range of the statements that should be performed get linked up with the perform statement only when the later is executed.
175
PERFORM with TIMES option: PERFORM para-2 5 times. PERFORM para-2 thru para-4 5 times.
PERFORM with UNTIL option:Perform para-2 UNTIL i>5.PERFORM para-2 THRU para-4 UNTIL k>n
PERFORM with VARYING option: PERFORM para-2 VARYING I from 1 by 1 UNTIL
i>20.
176
GOTO: GOTO procedure –name
Ex: GOTO correction-routine. STOP RUN:
177
Arithmetic verbs:
ADD:Add value TO data-name. ADD values GIVING data-name.
Example: ADD AB TO AMOUNT. ADD 20 TO TOTAL. ADD NI,N2 TO TOTAL.
INVALID STATEMENTS: ADD ‘223’ TO TOT-ITEM. ADD TOTAL TO 920 ADD VAT TO ‘TOTAL’ ADD 25.50 TO TOTAL
178
ANOTHER FORMAT OF ADD:
VALID: ADD P,Q GIVING X. ADD 5,TIME GIVING T. ADD X,Y,3,N GIVING SUN-1,SUM-2
INVALID: ADD A TO B GIVING C. ADD A AND B GIVING C ADD AB GIVING C
The reserve word TO,AND, is not allowed.
179
Example:
Identification division. Program-id digisum. Author tdm Environment division. Data division. Working-storage section. 77 sum pic 99 01 given-no 03 dig-3 pic 9 03 dig-2 pic 9 03 dig-1 pic 9
180
01 PART-SUM 03 PART-2 PIC 9 03 PART-1 PIC 9 PROCEDURE DIVISION Start DISPLAY “enter four-digit number” ACCEPT GIVEN-NO ADD-DIGIT ADD DIG-3,DIG-2 GIVING SUM ADD DIG-1 TO SUM MOVE SUM TO PART-SUM ADD PART-2 ,PART-1 GIVING SUM MOVE SUM TO PART-SUM DISPLAY “SUM OF DIGITS IN THE NUMBER IS: “ , PART-1 STOP RUN
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EXAMPLE WITH ACCEPT AND DISPLAY CLAUSE:
IDENTIFICATION DIVISION PROGRAM-ID EX-2 AUTHER TDM ENVIRONMENT DIVISION CONFIGURATION SECTION SOURCE-COMPUTER IBM-PC OBJECT-COMPUTE IBM-PC DATA DIVISION
WORKING-STORAGE SECTION 77 SUM PIC 99 01 GIVEN-NO
03 DIG-1 PIC 9 03 DIG-2 PIC9 03 DIF-3 PIC 9 03 DIG-4 PIC 9
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01 PART-SUM 03 PART-1 PIC 9 03 PART-2 PIC 9
PROCEDURE DIVISION ST-1
DISPLAY (1,1,) ERASE DISPLAY (10,10)”ENTER AFOUR DIGIT NUMBER” ACCEPT(10,40) GIVEN-NO ADD DIG-1, DIG-2 GIVING SUM ADD DIG-3, DIG-4 TO SUM MOVE SUM TO PART-SUM ADD PART-1, PART-2 GIVING SUM MOVE SUM TO PART-SUM DISPLAY (112,10) “SINGLE DIGIT IS”,PART-2 STOP RUN.
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SUBTRACT STATEMENT: To subtract one or the sum of two or more numeric
data items from one. To set the value of one or more items equal to the
result. Format:
Subtract id-1 or nl-1 from id(s) Subtract id-1 or nl-1 FROM id or nl GIVING id(s)
Example: SUBTRACT A FROM B SUBTARCT 20 FROM X SUBTRACT A,B FROM C SUBTRACT A FROM C,D SUBTRACT A,B FROM C,D
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EXAMPLE: SUBTRACT A FROM B GIVING C SUBTRACT 80 FROM 50 GIVING C SUBTTRACT TAX,PF FROM GROSS GIVING NET.
MULTIPY STATEMENT: Used to multiply numeric data items. MULTIPLY VALUE BY DATA-NAME. Rules: All operands must be numeric items except id(s) after
GIVING . Example:
MULTIPLY A BY B MULTIPLY 10 BY A MULTIPLY A BY B GIVING C MULTIPLY 10 BY A GIVING C,D
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More on multiply statement: Example: program to convert temp from cel. To Fahrenheit. IDENTIFICATION DIVISION PROGRAM-ID DIVISION ENVIRONMENT DIVISION DATA DIVISION WORKING-STORAGE SECTION. 77 CENT-TEMP PIC 999V99 77 FAR-TEMP PIC 999V999 77 TEMPORARY PIC 999V999 PROCEDURE DIVISION START-1
DISPLAY “TYPE IN TEMP. IN CENTIGRATDE IN FORM 999.99” ACCEPT CENT-TEMP. MUTIPLY CENT-TEMP BY 1.8 GIVING TEMPORARY. ADD TEMPORARY,32 GIVING FAR-TEMP. DISPLAY “TEMPRATURE IN FAHRENHITE IS”,FAR-TEMP. STOP RUN.
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DIVIDE STATEMENT: TO DIVIDE DATA ITEM INTO ANOTHER AND
SO ON. EXAMPLE:
DIVIDE A INTO B DIVIDE 4 INTO X. DIVIDE Y INTO X.
ILLEGAL STATEMENT: DIVIDE C INTO 9.5 DIVIDE X,Y INTO Z.
FORMAT-2 DIVIDE …… INTO ….. GIVING ….. DIVIDE A INTO B GIVING C DIVIDE 5.1 INTO 10.5 GIVING D
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FORMAT-3 DIVIDE … INTO….GIVING…..REMAINDER DIVIDE… BY….GIVING….REMAINDER.
EXAMPLE: DIVIDE A INTO B GIVING Q REMAINDER R DIVIDE A BY B GIVING Q REMAINDER R
ROUNDED OPTION: IF FIGURE IS 80.236 THEN IN ROUNDED FORM IS
80.24 THE EXCESS DIGIT IN RIGHT IS DROPPED. THE LAST DIGIT IS INCREASED BY 1. ROUNDED IS DONE ONLY AFTER DECIMAL
ALIGNMENT. ROUNDED OF NEGTIVE RESULT IS DONE BY
ROUNDING THE ABSOLUTE VALUE AND MAKING THE RESULT NEGTIVE.
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EXAMPLE: ADD A TO B ROUNDED ADD A TO B GIVING A ROUNDED. SUBTRACT 10 FROM SALES ROUNDED. MULTIPLY P BY Q GIVING R ROUNDED. DIVIDE S INTO T GIVING Q ROUNDEDE
REMAINDER R.
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SIZE ERROR OPTION: Due to insufficient size the size error occurred. The SIZE ERROR option is written immediately after any
arithmetic operation. Format:
ON SIZE ERROR Ex:
ADD A B GIVING C ON SIZE ERROR ROUNDED ON SIZE ERROR: ADD A TO B ROUNDED ON SIZE DISPLAY” RESULT IS TOO
LARGE” In this rounded effect the last digit in PIC clause while SIZE
ERROR is concerned with value and size given in the data item. We can also use the ; separating the ON SIZE ERROR clause
from the rest of the arithmetic statement. DIVIDE COMMISION BY SALES-MEN GIVING AVG-COMM
ROUNDED ON SIZE ERROR GO TO ERR-PARA.
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THE COMPUTE VERB: ARITHMATIC OPERATION EXPRESSION: The compute verb is used in arithmetic expression. GROSS-DEDUCTIONS (1+RATE/100)*N Writing COBOL Expression: P+Q-R Precedence rule for expression evaluation: Perform all unary – and + first. ** next. * and / next. Add and subtract ( binary + and -) last in the order in
which they appear. Scan the exp. From left to right. Example: A+B/C-D
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PARENTHESIS: (A+B)/(C+D) COMPUTE VERB: COMPUTE data-name =arithmetic expression Example: COMPUTE NETPAY =GROSS-DED COMPUTE OVERTIME=(HRS-WORKED-
100)*(RATE*1.9) COMPUTE A+B=(P+N)/100 COMPUTE X=5, COMPUTE SUM=TOTAL COMPUTE SUM=TOTAL, MOVE TOTAL TO SUM COMPUTE SUM, GROSS=BASIC+DA+HRA COMPUTE X=*DEPOSIT/100
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COMPUTE ROUNDED:
COMPUTE data-name ROUNDED =arithmetic expression
COMPUTE NET-VALUE ROUNDED=GROSS-DISCOUNT
COMPUTE…SIZE ERROR: When computed value is large and size defined in
the PIC clause is not sufficient to hold the value. Example:
COMPUTE P=Q/2*T ON SIZE ERROR PERFORM ERR-B THRU ERR-R
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COMPUTE USAGE: A data name declared Numerical data can be stored
through DISPLAY and COMPUTATIONAL (COMP) form. If it is in DISPLAY editing and displaying is easier. but in calculations it takes a lot of time hence inefficient. if a data name participates in calculations number of times, then it is advised to declare the items the data item as USAGE COMP.
as DISPLAY may be converted to COMP form: 03 NETPAY pic 999v99 WORKING STORAGE SECTION 03 WS-NET PIC 9999V99 USAGE COMP PROCEDURE DIVISION MOVE NETPAY TO WS-NET
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CONDITION: It is an entity which have one or more value in a given
time. Types:
Relational condition Sign condition Class condition Condition-name condition Negated simple condition Compound condition
If condition: Check if the result is true/false SALES IS LESS THEN 50000
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IF SALES IS LESS THAN 50000 MOVE BASIC TO SALARY ELSE COMPUTE SALARY=BASIC+BASIC*0.1
RELATIVE CONDITIONS: HAS SIMILAR NAME LIKE RELATIONAL EXPRESSION,
LOGICAL EXPRESSION ,LOGICAL CONDITION, CONDITIONAL EXPRESSION. Compare two expressions. when both are numeric items USAGE of both may be diff.First operand is called subject and second operand is called object
IS [NOT] GREATER THAN IS [NOT]> IS [NOT] LESS THAN IS [NOT]< IS [NOT] EQUAL TO IS [NOT]=
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IF SENTENCE: IF SENTENCE –first form
IF GROSSPAY IS GREATER THAN 150000 COMPUTE TAX=(GROSSPAY-100000)*0-10 ADD TAX TO GROSS-TAX. If statement is true then seq. of statement following the IF is
carried out e\ELSE statements up to full stop( . ) are not executed.
IF SENTENCE –second form IF GROSS PAY <150000 COMPUTE TAX=GROSSPAY*0.10. ELSE COMPUTE TAX=GROSSPAY*0.5. obserb the placement of ( .) after the complete IF statement.
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More on relative conditions: Two types: Comparison of numeric operands Comparison of non-numeric operands. Numeric operands: Depends upon two conditions; Sign of the number. Magnitude of the number.
When the decimal and packed decimal items are compared ,binary items are converted to packed decimal before the comparison begins.
025(999) 25(99) equal 10-(99-) 000+(99v99+) operand 1 is < operand 2 10001(9999v99) 110000(9999v9) operand 1 > operand 2
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Complete example of numeric comparison :
check odd/even IDENTIFICATION DIVISION PROGRAM-ID IF-STATE
AUTHER ABC. ENVIRONMENT DIVISION.
DATA DIVISION. WORKING-STORAGE SECTION
77 NUMBER PIC 9(4) 77 REMAIN PIC 9
PROCEDURE DIVISION DISPLAY “TYPE A 4-DIGIT NUMBER:”
ACCEPT NUMBER DIVIDE NUMBER BY 2 GIVING NUMBER REMAIN IF REMAIN EQUAL TO 0 DISPLAY “ THE NUMBER IS EVEN” ELSE DISPLAY “ THE NUMBER IS ODD” STOP RUN
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NON-NUMERIC OPERANDS:
Comparison of two non-numeric operand ,need not to be variables. they are either <,> or =.at least one of them may be non-numeric like ”ABC”.if one of the operand is numeric then also it is considered as alphanumeric and comparison takes pace accordingly.
IF NAME-1 IS EQUAL TO NAME-2 MOVE DESIG TO POST ELSE MOVE DESIG TO POSTING. Alphanumeric comparison is done by comparing the value of the
characters starting from left to right. Compare until two chanter are found that are not equal or until the end of the file is reached.
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NON-NUMERIC OPERANDS:
Secondly if the operands are of equal size. If operands are of diff. length the shorter operand
is extended on the right side by the required blanks to make both operands equal
A250 9250 OP1 >OP2 450 45J OP1<OP2 MNOPQ ABC OP1>OP2 PQRb PQR op1=op2 Abc2 abc op1>op2
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IF-CLASS CONDITION
Check whether is numeric or alphabetic IF SUM IS NUMERIC (between 0-9) IF NAME IS ALPHBETIC ( between a-z) Example: 05 AGE PIC S9999 IF AGE IS NUMERIC PERFORM TEST-1 ELSE PERFORM TEST-2 05 TCOD PIC A IF TCOD IS ALPHBETIC MOVE FAST TO NEW-MAST
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NESTED –IF STATEMENT: If within another IF is called as nested IF Syntax: i) IF statement….
If statement … ELSE ….. …
ii) IF Statement… IF statement…. ELSE ELSE IF ….
ELSE NEXT SENTENCE.
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EXAMPLE:
IF EMP-CODE=1 IF DAYS-WORKED IS GREATER THAN 200 MOVE ONE TO BONUS-CODE ELSE NEXT SENTENCE ELSE IF DAYS-WORKED IN GREATER THAN
250 MOVE 2 BONUS-CODE ELSE NEXT SENTENCE.
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SIGN CONDITION: This determines whether or not the algebraic value of an arithmetic
expression is <,>,= An operand is Positive is value>0 Negative if value<0 Zero if value=0 Example: IF AMOUNT IS NOT ZERO MOVE AMOUNT TO NEW-AMOUT ELSE MOVE OLD-AMOUNT TO NEW-AMOUNT Example2: IF P*Q IS POSITIVE PERFORM COMPT ELSE PERFORM ERR-PROC.
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IF-PRGRAMMING EXAMPLE:
PROBLEM: Fix-deposit interest criteria of a bank is >=3 years 10% =1 and <3 years 9% Program:
IDENTIFICATION DIVISION PROGRAM-ID FIXED-DEP AUTHER ABC
ENVIRONMENT DIVISION DATA DIVISION WORKING-STORAGE SECTION
77 DEP-NO PIC X(5)77 DEP-NAME PIC X(25)
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77 DEPOSIT PIC 9(6) 77 DEP-TIME PIC 99 77 INT PIC 999V99 01 OUT-REC 03 FILLER PIC X(5) VALUE SPACES 03 O-DEP-NAME PIC X(25) 03 FILLER PIC X(25) VALUE SPACES 03 O-DEP-YEARS PIC X(25) VALUE SPACES -3 O-PER PIC 99 03 FILLER PIC X(5) VALUE SPACES 03 O-INT PIC 9999.99 03 FILLER PIC X(25) VALUE SPACES 03 NET-AMNT PIC x(9)V99
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PROCEDURE DIVISION DISPLAY “DEPOSITOR NAME=30 CHARACTERS” ACCEPT DEP-NAME DISPLAY”YEARS OF DEPOSIT-2 DIGITS” ACCEPT DEP-TIME SEL-INT MOVE DEP-NAME TO O-DEP-NAME MOVE DEP-TIME TO O-DEP-YEARS IF DEP-TIME IS LESS THAN 3 MULTIPLY DEP-AMNY BY 0.09 GIVING INT ELSE MULTIPLY DEP-AMNY BY 0.10 GIVING INT
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ADD INT DEP-AMNT BY 0.20 GIVING INT MOVE INT TO O-INT DISPLAY OUT-REC STOP RUN.
CLASS CONDITION: Check whether the value of operand is numeric
or alphanumeric. Identifier IS [NOT] NUMERIC/ALPHBETIC
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RULES FOR CLASS CONDITION:
Name of the identifier should be DISPLAY or some form of DISPLAY.
For numeric option the identifier should be either numeric/alphanumeric.
For alphabetic option the identifier must be alphabetic/alphanumeric
It may be a group item. However for numeric option group item must not contain elementary items
E.g if non-numeric value is stored in numeric value an error will occur but not displayed.
IF GROSS-PAY IS NOT NUMERIC GO TO PARA-ERROR.
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CONDITION-NAME CONDITION:
This is itself a condition and have true/false condition. Can not be defined independently. Always associated with a condition variable. Can be defined in any section of DATA DIVISION.
And must be placed immediately after the conditional variable.
May be more than one condition name. A condition name either have a single variable or
have a set of values. Condition may be true/false. 88 condition name value/values is/are literel-1 thru
literal-2 literal-3 thru literal-4
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RULES FOR CONDITION-NAME
Condition name are mentioned at level no 88. Works as per naming rules. if same name is used
in more then one place, the condition name must be qualified by the name of its conditional variable.
The name of the conditional variable can be used as a qualifier for any of the condition name.
The value specified by the VALUE clause in the condition name entry must not conflict with the data desc of the conditional variable.
When THRU clause is used literal-1 must be less then literal-2 and so on.
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A conditional variable can be any elementary item or group item
77 TAX-PAYERS-TATUS PIC 9 88 INDIVISUAL VALUE IS 1 88 HUF VALUE IS 2 88 PROPERIETER VALUE IS 3 88 PARTNERSHIP VALUE IS 4 88 SENIOR-CITIZEN VALUE ARE 1,4 88 VALID-STATUS VALUE ARE 0 THRU 4
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The following statements can be used in the above mentioned structure:
IF HUF SUBTRACT 150000 FROM GROSSPAY
IF PROPRIETOR SUBTRACT 195000 FROM GROSS-PAY
IF NOT VALID -STATUS GO TO ERROR -IN- STATUS
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NEGATED SIMPLE CONDITION;
Any of the simple condition can be preceded by the logical operator NOT. This operator reverse the condition of the condition.
This can be used in two ways- in simple conditions it can be used as a part of the condition.---it can be precede a simple condition a simple condition to make it a negated simple condition.
Example: TAX NOT LESS THAN 100000 Another (second way ) is NOT LESS THAN
100000
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COMPOUND CONDITION:
Two simple conditions can be connected by the logical operators AND or OR to form a compound condition.
Exp: BALANCE GREATER THAN 999 AND
BALANCE LESS THAN 100001.
BALANCE GREATER THAN 999 OR BALANCE LESS THAN 100001.
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COMPOUND CONDITION: EXAMPLE
Sorting of numbers: SORTING-NUMBERS
PERFORM SORTING VARYING 1 FROM 1 BY 1 UNTILL I=N OR NO-EXCHANGE
SORTING MOVE 0 TO EXCHANGE-FLAG SUBTRACT 1 FROM N GIVING K PERFORM COMPARISON
VARYING J FROM 1 BY 1 UNTIL J>K COMPARISON
SET A1 TO J IF NUMBER(A1)>NUMBER(A1+1) MOVE NUMBER(A1) TO TEMP
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MOVE NUMBER (A1+1) TO NUMBER (A1) MOVE TEM TO NUMBER(A1+1) MOVE 1 TO EXCHANGE –FLAG
Entries for WORKING-STORAGE SECTION 01 DATA-ENTRY FOR SORTING-NUMBERS
02 I PIC 9(3) 02 J PIC 9(3) 02 K PIC 9(3) 02 N PIC 9(3) 02 EXCHANGE-FLAG VALUE IS ZERO 02 TEMP PIC 9(6)V99
The above program can be sorted by using the statement
PERFORM SORTING.
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FILE-ORGANIZATION
-Sequential files
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TYPE OF FILES;
Sequential files Index sequential files Direct files Sequential files:
Records are arranged on the basis on the basis of their physical locations in the files.
Records are according to the key as well as in the physical sequence.
Creation of the file is easy. Only you can go forward. Most of the records are processed each time file is
read. Can be organized in all storage devices like tape,disk.
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CREATION OF SEQ. FILE ON DISK:
In order to specify that a file will b eon the tape or disk certain enteries must be specify the FILE-CONTROL section.
ENVIRONMENT-DIVISION INPUT-OUT SECTION. FILE CONTROL SELECT file-name ASSIGN TO system-name [; RESERVE interger-1 (AREA AREAS)] [; ORGANIZATION IS SEQUENTIAL] [;ACCESS MODE IS SEQUENTIAL] [; FILE STATUS is data-name]
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SWLECT clause is must and must be specified first. ASSIGN clause specifies the association of file to a storage media. ORGANIZATIO specify the logical structure. ACCEES specify in which read and write operations are done. FILE STATUS is optional EXAMPLE:
ENVIRONMENT DIVISION INPUT-OUTPUT SECTION FILE-CONTROL SELECT EMP-IN-FILE ASSIGN TO DISK. ORGANIZATION IS SEQUENTIAL. ACCESS MODE IS SEQUENTIAL. FILE STATUS IS EMP-FIL-STATUS
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SEQUENTIAL FILES: DATA DIV. ENTRIES
FD file name BLOCK CONTAIN clause. LEVEL RECORDS clause.
Every file must be defined within FD ,defined in FILE-SECTION which is first section of DATA DIV, FD is heading must be in Area A and remaining part will be in Area B.
Example:FD STOCKLEVEL RECORS ARE OMMITED.BLOCK CONTAINS 12 RECORDS.RECORD CONTAINS 128 CHARACTERSDATA RECORD IS TARTS-REC
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SEQUENTIAL FILES: PROCEDURE DIVISION ENETERIES:
To use the file they must be opened with the appropriate phrases INPUT,OUTPUT or I_O in OPEN statement.
For reading a file –READ … AT END statement is used.
WRITE statement is used to write a file. If the file is printer file ADVANCING option to control the page movement.
After the job is completed file must be CLOSED. We can create a seq. file on disk directly from the
terminal. Data packages are available to do so, data is entered through the terminals. If data package is not available we can create seq file through terminal.
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IDENTIFICATION DIVISION PROGRAM-ID DISK-FILE –CREATION AUTHER ABC ENVIRONMENT DIVISION INPUT-OUTPUT SECTION FILE-CONTROL
SELECT MASTER-FILE ASSIGN TO DISK
DATA DIVISION FILE SECTION
FD MASTER-FILE BLOCK CONTAINS 12 RECORDS LEVEL RECORDS ARE STANDARD. 01MASTER-REC PIC X(80)
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WORKING-STORAGE SECTION. 01 TERMINAL-REC 03 T-NUMB PIC 9(5) 03 T-NAME PIC X(30) 03 T-ADDRESS PIC X(45)
PROCEDURE DIVISION MAIN-LOGIC
OPEN OUTPUT MASTER-FILE PERFORM GET-INPUT PERFORM BUILD-DISK UNTIL T-NUMB=99999 CLOSE MASTER-FILE
BUILD-DISK WRITE MASTER-REC FROM TERMINAL-REC PERFORM GET-INPUT
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GET-INPUT DISPLAY ‘ ENTER EMPLOYEE NUMBER (5 DIGITS’ ACCEPT T-NUMB DISPLAY ‘ENTER EMPLOYEE NAME (30
CHARACTERS)’ ACCEPT T-NAME DISPLAY ‘ENTER EMPLYEE ADDRESS (45
CHARACTERS)’ ACCEPT T-ADDRESS
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SEQ. DATA FILE ON DISK PROGRAMMING
To create a seq. file of emp. In an organization. output layout should be 1-5 Employee number6-35 Employee Name36-80 Address
IDENTIFICATION DIVISION
PROGRAM-ID EMP-CREATE-SEQ-FILE
AUTHER ABB
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
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SELECT MASTER-FILE ASSIGN TO DISK. DATA DIVISION. FILE SECTION. FD MAIN-FILE
LEVEL RECORDS ARE STANDARD VALUE OF FILE-ID IS ‘MAIN.DAT’
01 MASTER-REC PIC X(80). WORKING-STORAGE SECTION 01 TERMINAL-REC
03 T-NUMB PIC 99999 03 T-NAME PIC X(30) 03 T-ADDRESS PIC X(45)
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PROCEDURE DIVISION MAIN-LOGIC
OPEN OUTPUT MAIN-FILE PERFORM GET-INPUT PERFORM BUILD-DISK UNTIL T-NUMB=99999 CLOSE MAIN-FILE. STOP RUN. BUILD DISK. WRITE MASTER-FILE FROM TERMINAL-REC. PERFORM GET-INPUT. GET-INPUT. DISPLAY(1,1) ERASE. DISPLAY(3,5) ‘ENTER EMPPLOYEE CODE (5 DIGIT)’ DISPLAY (5,5) ‘ENTER EMPLOYE NAME(30 CHARS’ DISPLAY (7,5) ‘ENTER ADDRESS(45 CHARACTERS)’
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ACCEPT (3,45) T-NUMB ACCEPT (5,45) T-NAME ACCEPT (7,45) T-ADDRESS
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UPDATING A SEQUENTIAL FILE: Creation of one or more disk files from existing seq.
file Updating data of master file. Updating data of master file using the transaction
file. Disk file can be updated using a single file b’coz that
can be opened in i-o mode both for read and write. Tape file can be used only for input or output one at a
time . To update a tape file we have a to create a new file.
Existing file is read-in one at a time. Changes can be made to any or all records but each record if changed must be written to output tape otherwise will be lost.
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Ex.:- suppose we have a master file with records
about an employee. We need to change pension-code on the records of all women employees by setting pension-code equal to X.
PROCEDURE DIVISION. MAIN-LOGIC OPEN INPUT OLD-FILE OUTPUT NEW-FILE READ OLD-FILE AT END MOVE ‘Y’ TO FILE-EOF. PERFORM UPDATE-FILE UNTIL FILE-
EOF=‘Y’
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CLOSE OLD-FILE NEW-FILE STOP RUN UPDATE-FILE IF SEX-CODE=‘F’ MOVE ‘X’ TO PENSION=CODE WRITE NEW-REC FROM OLD-REC READ OLD-FILE AT END MOVE ‘Y’ TO FILE-
EOF
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ANOTHER EXAMPLE:
Another type of creation data from a disk file called QTYFILE is to used to control CALCFILE ans TRS-FILE
QTYFILE: 1-5 account number 6-7 month 8-9 day 10-13 qty1 14-17 qty2 18-21 qty3 22-25 qty4
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CALCFILE AND TRSFILE: 1-5 account number 6-7 month 8-9 day 10-14 sum 15-19 sum2 20-24 difference 25-34 product1 35-40 product2 41-45 quotient 45-50 remainder 51 code1
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Atleast one of the four field quantity 1,2,3,4 in the QTYFILE is >=14 then record is created iin CALCFILE .if three fields are <14 then records are created on TFILE .both CALFILE,TFILE have same record.
Formulas are; Sum1=qty1+qty2+qty3 Diff=qyu4-qty3 Product1=qty3*qty2 Prod2=qty3*qty2 Quotient=q1+q2+q3/q2 with remainder in remain Code=M if q2<100,N if q2>100,P if q2=100.
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SOLUTION: IDENTIFICATION DIVISION
PROGRAM-ID SEQ-FILS-CRE. AUTHER SWARN ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT QTYFILE ASSIGN TO DISK. ORGANIZATION IS SEQUENTIAL. ACCESS IS SEQUENTIAL. SELECT CALCFILE ASSIGN TO DISK. ORGANIZATION IS SEQUENTIAL. ACCESS IS SEQUENTIAL. SELECT TRSFILE ASSIGN TO DISK. ORGANIZATION IS SEQUENTIAL. ACCESS IS SEQUENTIAL.
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DATA DIVISION. FILE SECTION. FD QTYFILE BLOCK CONTAINS 26 RECORDS RECORD CONTAIN 25 CHARACTERS. LABEL RECORDS ARE STANDARD. 01 QREC. 03 QTY-ACCNO PIC X(5) 03 QTY-MONTH PIC 99 03 QTY-DAY PIC 99 03 QTY-1 PIC S99V99 03 QYY-2 PIC S99V99 03 QTY-3 PIC S99V99 03 QYY-4 PIC S99V99
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FD CREC RECORD CONTAINS 51 CHARACTERS BLOCK CONTAIN 11 RECORDS LABEL RECORDS ARE STANDARD. DATA RECORD IS CREC. 01 CREC 03 CALC-ACCNO PIC X(5) 03 CALC-MONTH PIC 99 03 CALC-DAY PIC 99. 03 SUM-1 PIC S999V99 03 SUM-2 PIC S999V99 03 DIFFERENCE PIC S999V99 03 PRODUCT1 PIC S9(4)V9999 03 PRODUCT2 PIC S9(4)V. 03 QUOTIENT PIC S9(3)V99 03 REMAIN PICS9999 03 CODE1 PIC X
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FD TRSFILE RECORD CONTAINS 51 CHARACTERS BLOCK CONTAIN 11 RECORDS LABEL RECORDS ARE STANDARD. DATA RECORD IS TREC. 01 TREC PIC X(51) WORKING-STORAGE SECTION. 77 WSUM PIC S999V99 77 EOF-FLG PIC X VALUE ‘N’ PROCEDURE DIVISION. MAIN-ROUTINE. OPEN INPUT QTYFILE. OUTPUT CALCFILE TRSFILE READ QFILE AT END MOVE ‘Y’ TO EOF-FLAG. PERFORM PROC-ROUTINE UNTIL EOF-FLAG=‘N’ CLOSE QTYFILE CALCFILE TRSFILE. STOP RUN.
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PROC-ROUTINE MOVE QTY-ACCNO TO C-ACTNO. MOVE QTY-MONTH TO C-MONTH. MOVE QTY-DAY TO C-DAY. ADD QTY1 QTY2 QTY3 GIVING SUM1. SUBTRACT QTY4 FROM QTY3 GIVING DIFFERENCE. MULTIPLY QTY3 BY QTY2 GIVING PROD1. MULTIPLY QTY3 BY QTY2 GIVING PROD2 ROUNDED. ADD QTY1 QTY3 QTY4 GIVING WSUM. DIVIDE QTY-2<100 MOVE ‘M’ TO CODE1. ELSE IF QTY-2>100 MOVE ‘N’ TO CODE1.
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IF QTY-1<10 AND QTY-2 <10 AND QTY <10 WRITE TREC FROM CREC. ELSE WRITE CREC. READ QTYFILE AT END MOVE ‘Y’ TO EOF-
FLAG.
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REWRITE STATEMENT:
A disk seq file can be opened in i/o to allow to read and write to same file.there is one statement in COBOL to update the seq.file –REWRITE statement.It replaces the logical record accessed by the previous READ statement with the contents of the specified record.
Format is: REWRITE record name [FROM identifier] REWRITE EMP-REC REWRITE LEAVE-REC FROM WORK-REC.
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. POINTS TO BE REMEMBER WHILE REWRITE
STATEMENT: The file associated with the record name must be
disk file. File must be opened in i/o mode. REWRITE replaces the record that has was accessed
by the most recent READ statement. Length of the record referenced by record name in the
REWRITE statement must be equal to the length of the record that is being replaced.
Current record pointer is not effected by the execution of the REWRITE statement.
REWRITE …..FROM is equivalent to MOVE identifier TO record name REWRITE record name
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UPDATING SEQ. FILE :ACCESSING RECORDS. Before updating file must be read which is possible only
after accessing the record.Two types of files are – Master file and Transaction File.
Master File:- each record contains a identifying field which is called key field (unique one) ,can be a number or name/combination of both. Records are arranged in seq according to the key.
Transaction file:- each record contain a key and has fewer records as compared to master file ,records are sorted on same key-seq as in master file.
In order to access a record in seq file we have to read every proceediing record in that file.after each READ key seq. no. are to be compared.when they are equal matching record is accessed.required action is to be taken on the information of the record.
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Proceed with the following steps: Read first transaction record-1080 Read first master file-1078 Compare the key fields,here these fileds are not equal Tran#>master# Now read next master record i.e 1080. Compare both key fields.Now these fields are equal Tran#=mat3 Desired record is found in the master file,display
YES-if found and so on
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The logic can be as follow: If trans-key>mast-key Get new master record. Else If trans-key=mast=key Handle mast-achieved Else Handle no-match End if Points to be noted: If trans file ends before master file stop the execution of the
program. It means theres is no more records to be accessed. If master file reaches its end before the transaction file then
print “NOT FOUND” for each record in the transaction file.
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UDATING SEQ. FILE-PROGRAM FOR ACCESSING RECORDS: PROCEDURE DIVISION MAIN-LOGIC OPEN INPUT MASTER-FILE TRANS-FILE OUTPUT OUT-FILE PERFORM GET-MASTER PERFORM GET-TRANS PERFORM PROCESS-RECS UNTIL T-EOF=‘Y’ OR M-
EOF=‘Y’ IF M-EOF=‘Y’ PERFORM NO=MATCH UNTIL T-EOF=‘Y’ CLOSE MASTER-FILE TRANS-FILE OUT-FILE. GET-MASTER READ MASTER-FILE AT END MOVE ‘Y TO M-EOF
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GET-TRANS READ TRANS-FILE AT END MOVE ‘Y’ TO T-EOF PROCESS- RECS IF T-KEY>M-KEY PERFORM GET-MASTER. ELSE IFT-KEY=M-KEY PERFORM GET-MASTER ELSE PERFROM NO-MATCH. MATCH-HIT MOVE M-KEY TO OUT-KEY MOVE ‘YES-FOUND’ TO OUT-MESSAGE. WRITE OUT-REC
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PERFORM GET-TRANS PERFORM GET-MASTER. NO-MATCH MOVE T-KEY TO OUT-KEY MOVE ‘ NOT FOUND ‘ TO OUT-MESSAGE. WRITE OUT-REC PERFORM GET-TRANS.
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UPDATING SEQ. FILE:ADDING RECORDS: WHEN NEW RECORDS ARE ADDED THESE NEW RECORDS
ARE TO BE INCORPORATED TO MASTER FILE.RECORDS CAN NOT BE ADDED TO SEQ. FILE DIRECTLY WHETHER THE FILE IS ON TAPE OR DISK. THE MAMSTER FILE MUST BE COPIED,ONE RECORD ATA TIME, WITH NEW RECORD INSERTED AT THE APPROPRIATE LOCATIONS.
YRANSACTION FILE MASTER FILE 801 789 863 800 864 863 -- 865 -- 866
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801 IS TO BE INSERTED IN BETWEEN 800 AND 863. 863 ALREADY RECORD SEXITS,IT IS
ADUPLICATE,PRINT AN ERROR MESSAGE. 864 INSERT BETWEEN 863 AND 865. PSEDO CODE CAN BE AS UNDER; If trans-key >mast-key Copy old-master to new-master. Else If trans-key<mast-key Write trans-rec on new-master Else Handle dup;icate record end if End if.
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If master file ends first ,copy all the records in the transaction file on to the new master file.
If transaction file ends first copy all the remaining records of the old master file to the new master file.
PROCEDURE DIVISION MAIN-LOGIC OPEN OLD-MAST-F IF-F OUTPUT NEW MAST-F ERR-FIL PERFORM GET-OM-R PERFORM GET-T-R PERFORM ADD-RECS UNTIL OM-EOF =‘Y’ OR TRANS-EOF=‘Y’ IF OM-EOF=‘Y’ PERFORM COPY-FROM-TRANS UNTIL TRANS-EOF=‘Y’
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ELSE PERFORM COPY-FROM-OM UNTIL OM-EOF=‘Y’ CLOSE OLD-MAST-F,TRANS-F,NEW-MAST-F,ERR-FIL. STOP RUN. GET-OM-R READ OLD-MAST-F AT END MOVE “Y” TO OM-EOF GET-TRANS. READ TRANS-F AT END MOVE “Y” TO TR-EOF. ADD-RECS. IF T-KEY>MAST-KEY PERFORM COPY-FROM-OM ELSE IF T-KEY<MAST-KEY PERFORM COPY-FROM-TRANS
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ELSE PERFORM HANDLE-DUP COPY-FROM-OM WRITE NEW-MAST-R FROM OLD-MAST-R PERFORM GET-OM COPY-FROM-TRANS WRITE NEW-MAST-R FROM TRANS-REC PERFORM GET-TRANS HANDLE-DUP MOVE TRANS-REC TO ERR-DATA MOVE ‘DUPLICATE’ TO ERR-MESSAGE WRITE ERR-REC FROM E-REC PERFROM COPY-FROM –OM PERFORM GET-TRANS.