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COBOL for the 21st Century

Nancy Stern Hofstra University

Robert A. Stern Nassau Community College

James P. Ley University of Wisconsin-Stout (Emeritus)

John Wiley & Sons, Inc.11th edition

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Control Break Processing

Chapter 10

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Chapter Objectives

To familiarize you with

• Main types of computer-generated reports

• Techniques used for efficient printing of group reports and control totals

• Control break processing and control break printing

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Chapter Contents

• Introduction to Control Break Processing

• Program Requirements for Control Break Processing

• Multiple-Level Control Breaks

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Types of Reports

• Detail or Transaction Reports– Include one or more lines of output for

each input record read

• Exception Reports– Printout of individual records that meet

(or fail to meet) certain criteria

• Summary Reports– Summarizes rather than itemizes to

provide more comprehensive information

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Control Break Processing

• Produces summary report using control fields to indicate when totals are to print

• Records with same value for control field grouped together in file

• Totals printed for each group of records with same control field value

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Control Break Example

• Consider file of sales records, each with three fields: – Salesperson's department number,

salesperson's number, sales amount

• Department number is control field

• Records in sequence by control field– All records for salespeople in Dept 01

followed by records for those in Dept 02, …

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Sample Sales Input Data

01 12345 098855

01 12346 353700

01 12347 003499

02 12222 987700

02 12234 008777Amt-Of-Sales-In

SlsNo-In

Dept-In

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Control Break Example

• Report includes detail printing– One line for each record with salesperson's

amount of sales

• Report also includes summary lines or group printing – Total line written for each department– After all records for Dept 01 read and

printed, total for Dept 01 printed– Same is done for Dept 02, and so on

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Control Break Sample Report

Dept Salesperson No Amt of Sales

01 12345 $988.55

01 12346 $3,537.00

01 12347 $34.99

Total for Dept is $4,560.54

02 12222 $9,877.00

02 12234 $87.77

Total for Dept is $9,964.77

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Control Break Example

• Records must be in sequence by control field (department number)

• Sales records for Dept 01 read in, printed, Dept total accumulated

• Continues until record read in with different Dept number

• Change in Dept triggers printing of Dept total for Dept 01

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Single-Level Control Break

• Single-level means program has only one control field whose value triggers printing of totals

• Control break is change in control field value from one record to the next

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Single-Level Control Break

• Many steps (initialization, heading routines) same as previous programs

• Detail routine must be modified to check for control breaks

• New module added to handle control break processing

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Detecting a Control Break

• For first record read, move control field to hold area in WORKING-STORAGE

• If control field of subsequent records is same as hold area – Perform detail processing

• If they are not equal, control break occurs – Perform control break routine

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Detail Processing

When control field is equal to hold area

• Add amount to control total

• Print detail record (if desired)

• Read next record

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Control Break Routine

If control field of record read is not equal to hold area

• Print control total for previous group

• Initialize control total field to zero

• Reinitialize hold field with new control field value

• Perform detail processing as in previous step

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Handling first record

• First record has no previous control field value for comparison

• Add field to use as "flag" to determine if record is first one processed (e.g., First-Record initialized to 'YES')

• When record read, if First-Record = 'YES'– Save control field value in hold area– Turn "off" flag by setting it to 'NO'

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Forcing Final Control Break

• Totals printed when record with new control field is read

• Last group of records has no subsequent record to trigger printing

• Include statements in end of job routine to move final group total to output record and print it

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Printing a Final Total

• May accumulate final total by – Adding amount from each record to control

group total and final total in detail routine– Adding control group total to final total in

control break routine

• Second method more efficient since additions made once for each group instead of once for each record

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Multiple Level Control Breaks

• Suppose a sales record is created each time a salesperson makes a sale

• Each salesperson may have multiple sales records

• Report will include two levels of totals– Total sales for each salesperson– Total sales for each department

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Multiple Level Control Breaks

• Two control fields: Dept-In and SlsNo-In

• Records sorted by major control field (Dept-In)

• Within department, sorted by minor control field (SlsNo-In)

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Sample Sales Input Data

Dept-In SlsNo-In Amt-Of-Trans-In

01 004 127.23

01 004 100.14

01 006 027.45

01 006 052.23

01 006 126.27

02 003 111.14

02 003 027.23

In sequence within Dept 01

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Double-Level Control Break

• Two hold areas, one for each control field

• Check for control break on each – If no change in Dept-In or SlsNo-In, just

add Amt-Of-Trans-In to salesperson total– If Dept-In changes, perform major control

break routine– If no change in Dept-In but SlsNo-In

changes, perform minor control break routine

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Major Control Break Routine

• Begins by forcing minor control break– This processes last salesperson’s total for

previous department

• Print department total

• Reinitialize department total to zero

• Save new Dept-In in hold area

• Print heading for new department

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Minor Control Break Routine

• Print total for previous SlsNo-In

• Add salesperson total to department total

• Initialize salesperson total to zero

• Move new SlsNo-In to hold area

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Chapter Summary

• Control break program may have any number of control fields

• All input records must be in sequence by minor control fields within intermediate control fields within major control fields

• Sort file before processing if records are not already in this order

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Chapter Summary

• Control break routines– Higher-level breaks force lower-level

breaks– Appropriate control total line printed– Appropriate control total is initialized– Appropriate control field is initialized

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