Control Break Processing

1
Control Break Processing
COBOL for the 21st Century
11th edition
Stern, Stern Ley
John Wiley Sons, Inc.
Chapter 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

3
Chapter Contents

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

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

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

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,

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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
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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

9
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

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

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

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

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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

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

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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'

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

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

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

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)

21
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
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

23
Major Control Break Routine

• Begins by forcing minor control break
• This processes last salespersons total for
  previous department
• Print department total
• Reinitialize department total to zero
• Save new Dept-In in hold area
• Print heading for new department

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

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

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