Control Break Processing

1. 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 • 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 01 12345 098855 01 12346 353700 01 12347 003499 02 12222 987700 02 12234 008777 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 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

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 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 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