1. Control Break Processing
COBOL for the 21st Century
11th edition
Stern, Stern & Ley
John Wiley & Sons, Inc.
Chapter 10
Control Break Processing

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 Exception 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, …

7. Sample Sales Input Data
Amt-Of-Sales-In
SlsNo-In
Dept-In

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

9. Control Break Sample Report
Dept Salesperson No Amt of Sales
$988.55
$3,537.00
$34.99
Total for Dept is $4,560.54
$9,877.00
$87.77
Total for Dept is $9,964.77

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

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

14. 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

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'

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
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 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

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