The DATA DIVISION

1. Chapter 3 The DATA DIVISION

2. Chapter Objectives To familiarize you with • Ways in which data is organized in COBOL • Rules for forming data-names • Defining input and output files in DATA DIVISION • Defining storage for work fields and constants • Forming Data-Names • The FILE SECTION of the DATA DIVISION • Types of Data • WORKING-STORAGE SECTION of the DATA DIVISION

3. Interactive and Batch Programs • Fully Interactive Programs • Use ACCEPT to get input from keyboard • Use DISPLAY to display output on screen • Full Batch Programs • Get input from files on disk • Direct output to files on disk • Hybrid Programs • Use combination of interactive and batch input and output methods

4. COBOL Data Organization • Field - group of characters forming a meaningful unit or basic fact • Characters in a name or digits in an amount • Records - group of related fields • All fields related to customer • File - group of related records • Customer file made up of customer records

5. Identify the valid data-names • Date-Of-Birth • Amount$Out • Section • -First-Name • 98-6 • Time out

6. Data-Name Guidelines • Use meaningful data-names that describe contents of field • Amount-Due-In instead of A1 • Use prefixes or suffixes in data-names when appropriate • -IN and -OUT for fields (Emp-Salary-IN and Emp-Salary-OUT) • -FILE and -RECORD for file and record names (Emp-File and Emp-Record)

7. DATA DIVISION • Defines, describes storage for all data • Two main sections • FILE SECTION • Defines all input and output files, records, fields • Required for any program that uses files, typically batch programs • WORKING-STORAGE SECTION • Defines constants, end-of-file indicators and work areas • Defines fields not part of input or output files

8. Types of Files to Define • Input files • Master files • Transaction files -> updates • Output files • New Master files -> mix the two to get • Report files

9. File Description Entries • Each file described with an FD (File Descriptor) sentence • One FD for each SELECT statement in ENVIRONMENT DIVISION • FD followed by • File-name • Optional clauses to describe file and format of its records

10. File Description Format FD file-name RECORD IS OMITTED LABEL RECORDS ARE STANDARD RECORD CONTAINS integer-1 CHARACTERS BLOCK CONTAINS integer-2 RECORDS .

11. File Description clauses • LABEL RECORDS clause • Used if labels stored in file (OS will handle this for us, so we won’t use this clause) • BLOCKS CONTAINS clause • Indicates blocking factor for disk files (We won’t be using this clause) Has to do with disks that store data relative to blocks. • Just in case you see it later.

12. RECORD CONTAINS clause • Indicates size of each record • Optional but recommended since it provides check on record size • Given this FD FD Sales-File Record Contains 75 Characters. • If PICTURE clauses mistakenly add up to 76, compiler will report a syntax error

13. Defining a Record • Each FD (File Descriptor) followed by record description entries for the file • Data grouped in COBOL by levels • Record-name defined at the 01 level • Considered highest level of data • Fields within a record defined at subordinate level with level numbers from 02 to 49

14. Record Description Example 01 Employee-Rec-In. 05 Name-In … 05 Annual-Salary-In … 05 Job-Description-In … • Fields at 05 level subordinate to 01 level entry • All fields at same level (05), independent or not subordinate to each other • Leave room in numbering in case you need to add in between.

15. SELECT, FD, 01 entries & fields • REVIEW: • SELECT names file, assigns it to hardware device • FD describes file • 01 names record • 02-49 describes fields within record

16. Elementary and Group Items • Items defined with a level number are one of two types • Elementary item - field that is not further subdivided • Must include a PICTURE clause • Group item - field that is further subdivided • Has no PICTURE clause

17. Elementary and Group Items 01 Employee-Rec-In. 05 Name-In … 10 First-Name-In (Picture clause) 10 Last-Name-In (Picture clause) 05 Annual-Salary-In (Picture clause) • Name-In is group item since it is subdivided into first and last name • Employee-Rec-In also group item • First-Name-In is elementary item since it is not further subdivided

18. Invalid Level Numbers 01 Employee-Rec-In. 05 Name-In … 10 First-Name-In (Picture clause) 12 Last-Name-In (Picture clause) 05 Annual-Salary-In (Picture clause) • Last-Name-In level number is invalid since it is not subordinate to First-Name-In • Makes no sense because First-Name-In wouldn’t have a PIC clause and same indentation • Both first and last name are at same level and should have same level number

19. PICTURE (PIC) clauses • Specify type of data stored in field • Indicate size of field

20. Types of data fields • Alphabetic • Only letters or blanks • For name, item description, etc. • Alphanumeric • Any character - letters, digits, special characters • For an address like 123 N. Main St. • Numeric • Only digits • For fields used in arithmetic operations

21. Data Types in PICTURE clause • A for alphabetic • X for alphanumeric • 9 for numeric

22. Size of Data Fields Denote size of field by: • Number of A’s, X’s or 9’s used in PICTURE 01 Cust-Rec-In. 05 Cust-ID-In Picture XXXX. 05 Amt-In Picture 99999.

23. Size of Data Fields My also denote size of field by: • A, X or 9 followed by number in parentheses 01 Cust-Rec-In. 05 Cust-ID-In Picture X(4). 05 Amt-In Picture 9(5).

24. Defining Fields in Record • Must account for all positions defined in record layout • Must describe fields in order they appear in record • Field names should be unique • For fields not used by program • Data-name may be left blank (preferable) • May use reserved word FILLER as data-name • Positions must still be defined using PIC clause • Common for printing/display

25. Implied Decimal Point • For fields used in arithmetic operations • Symbol V used in PIC clause to denote location of implied decimal point • Decimal point itself not stored as part of number • To store value 26.79 in field AMT-IN, code entry as 05 Amt-In Pic 99V99.

26. Variable and Constant Data • Entries in DATA DIVISION reserve storage for data • Entries in FILE SECTION reserve storage for data from records in input/output files • WORKING-STORAGE SECTION reserves storage for keyed input/output

27. Constant Data • Data with a fixed value • Value that does not depend on input • Examples: • Fixed tax rate of .05 • Message “INVALID” displayed when a value is in error • .05 and “INVALID” are constant values

28. Types of Constants • Numeric literal • Examples: .05 5280 199.99 • Constant used for arithmetic operations • Nonnumeric (alphanumeric) literal • Examples: “INVALID” “Enter your name” • Figurative constant • SPACES ZEROS • Reserved word for commonly used values

29. Rules for Nonnumeric Literals • Must be enclosed in quotation marks • From 1 to 160 characters, including space • Any character in COBOL character set except quotation markValid Nonnumeric Literals '123 Main St.' '$14.99' '12,342' 'Enter a value from 1 to 10'

30. Nonnumeric Literals (use of quotes) • Only characters within quotes are moved or displayed • May contain all numbers ('125') but not same as numeric literal (125) • Cannot be used in arithmetic operations • Cannot be moved to field with PIC of 9’s • Are not data-names • 'Amount-In' not same as field defined in DATA DIVISION called Amount-In

31. Figurative Constants - ZERO • ZERO, ZEROS or ZEROES means all zeros Move Zeros To Total-Out • Fills each position in Total-Out with a zero • May be used with both numeric and alphanumeric fields Example

32. Figurative Constants - SPACE • SPACE or SPACES means all spaces or blanks Move Spaces To Code-Out • Fills each position in Code-Out with a space or blank • Use only with alphanumeric fields since blank is invalid numeric character Example

33. WORKING-STORAGE SECTION • Follows FILE SECTION • Begins with heading on line by itself • Starts in Area A, ends with period • All items must be defined at 01 level or in entries subordinate to 01 level entry

34. WORKING-STORAGE SECTION • Rules for user-defined data-names apply • Elementary items: • Must include PICTURE clause • May be assigned initial value with VALUE clause

35. Uses of WORKING-STORAGE To define fields used for • Keyed input and displayed output • Intermediate arithmetic results • Counters and totals • End-Of-File Indicators

36. VALUE clause • To define initial value for field • If omitted, field’s value undefined when program begins execution • May be used only in WORKING-STORAGE SECTION

37. VALUE vs MOVE • VALUE clause used in DATA DIVISION • Gives initial value before execution begins • MOVE used in PROCEDURE DIVISION • Assigns value to field after program begins • MOVE may change initial value of field

38. VALUE Clause • Contains literal or figurative constant • Data type must match PICTURE • Numeric literals or ZEROS used with PIC 9 fields 01 WS-Tax-Rate Pic V99 Value .06. 01 WS-Total Pic 999 Value Zeros. • Nonnumeric literals, ZEROS or SPACES used with PIC X fields 01 WS-EOF Pic X(3) Value ‘YES’. 01 WS-Descrip Pic X(8) Value Spaces.

39. Defining Constants or Literals Define a literal of .28 (28%) for a tax rate • Method 1 - code as literal in PROCEDURE DIVISION Multiply .28 by WS-Salary Giving WS-Tax • Method 2 - store in data item in WORKING-STORAGE SECTION 01 WS-Rate Pic V99 Value .28.

40. Defining Constants or Literals • Method 2 - use data-name in place of literal in PROCEDURE DIVISION Multiply WS-Rate by WS-Salary Giving WS-Tax • Preferable for literals used more than once • Reduces likelihood of error since literal value entered one time • Allows meaningful name to be associated with number

41. Continuation of Literals • Nonnumeric literals may be up to 160 characters • Long literals may not fit on one typed line • Subdividing long literals into separate fields is recommended • You may need this when making a long sentence.

42. Continuation of Literals Separate this report title into two fields "Transaction Report for XYZ Corporation" 01 Report-Title. 05 Pic X(18) Value 'Transaction Report'. 05 Pic X(20) Value ' for XYZ Corporation'. Example

43. Continuation of Literals • Long literals may be continued from one line to next, although this is not recommended • Rules for continuation of literals from one line to next • Begin literal with quotation mark. • Continue literal to position 72. Do not end with quotation mark. • Place hyphen on next line in position 7. • Continue literal with quotation mark starting anywhere in Area B. • End literal with quotation mark. • Example p. 92

44. COBOL 2008 Changes • LABEL RECORDS clause will be phased out entirely • VALUE clause will be allowed in FILE SECTION • Way to continue nonnumeric literals will change • Margins A and B rules will be guidelines rather than requirements • Commas and dollar signs will be permissible in numeric literals

45. Chapter Summary • Data organized into files, records and fields • Variable data changes with each run depending on input values • Constant or literal data defined within program, not entered as input

46. Chapter Summary • FILE SECTION includes FD entry for each file used by program • Record names coded at 01 level • Field names coded at 02-49 level • Fields must be defined in order they appear in record

47. Chapter Summary • Group items are further subdivided • Elementary items are not subdivided • Elementary items have PICTURE clause • Codes X, A, 9, V used to describe data

48. Chapter Summary • WORKING-STORAGE SECTION used for storing • Intermediate results, counters • End-of-file indicators • Interactive data accepted as input or displayed • VALUE clauses may be used in this section to initialize fields