COBOL for the 21

st 11th edition

Century

John Wiley & Sons, Inc .

Nancy Stern

Hofstra University

Robert A. Stern

Nassau Community College

James P. Ley

University of Wisconsin-Stout (Emeritus) 10-1

Chapter 10

Control Break Processing

10-2

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 10-3

Chapter Contents

• Introduction to Control Break Processing • Program Requirements for Control Break Processing • Multiple-Level Control Breaks 10-4

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 10-5

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 10-6

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, … 10-7

Sample Sales Input Data

01 12345 098855 01 12346 353700 01 12347 003499 02 12222 987700 02 12234 008777 Amt-Of-Sales-In SlsNo-In Dept-In 10-8

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 10-9

Control Break Sample Report

Dept Salesperson No 01 01 12345 12346 01 12347 Total for Dept is Amt of Sales $988.55

$3,537.00

$34.99

$4,560.54

02 12222 02 12234 Total for Dept is $9,877.00

$87.77

$9,964.77

10-10

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 10-11

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 10-12

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 10-13

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 10-14

Detail Processing

When control field is equal to hold area • Add amount to control total • Print detail record (if desired) • Read next record 10-15

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 10-16

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' 10-17

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 10-18

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 10-19

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 10-20

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) 10-21

Sample Sales Input Data

Dept-In SlsNo-In 01 004 01 01 004 006 Amt-Of-Trans-In In sequence within Dept 01 127.23

100.14

027.45

01 01 006 006 052.23

126.27

02 003 111.14

02 003 027.23

10-22

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 10-23

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 10-24

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 10-25

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 10-26

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 10-27

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