DATA DIVISION

Data division is used to define data needed to be accessed by the program. Ø        a.Describes input and output format of data in files...

Data division is used to define data needed to be accessed by the program.

Ø       a.Describes input and output format of data in files.

Ø       b.Defines any constants and work areas.

 The three sections of this division are:

1.FILE SECTION

Ø       Describes Record Structure of Files

2.WORKING-STORAGE SECTION

Ø       Succeeds file section

Ø       Used for intermediate storage

Ø       Common practice to group related items together.

3.LINKAGE SECTION

Ø       Describes data made available from another program.

     

1.FILE SECTION

File Description Entries

Ø       Each file described with an FD (File Descriptor) sentence

Ø       One FD for each SELECT statement in ENVIRONMENT DIVISION

Syntax:

FD  file-name

                                    RECORD IS                  OMITTED           

 LABEL

                                    RECORDS ARE            STANDARD 

 RECORD CONTAINS integer-1 CHARACTERS

             BLOCK CONTAINS integer-2 RECORDS.  

File Description clauses

LABEL RECORDS clause - Used if labels stored in file

BLOCKS CONTAINS clause - Indicates blocking factor for disk files

Both labels and blocking usually handled by operating systems so clauses will be omitted

RECORD CONTAINS clause

 - Indicates size of each record (Optional but recommended since it provides check on record size)

Defining a Record 

Ø          Each FD followed by record description entries for the file

Ø          Record-name defined at the 01 level -Considered highest level of data

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Ø          Fields within a record defined at subordinate level with level numbers from 02 to 49           

Example:

      01 Employee-Rec-In.
         05  Name-In …
         05  Annual-Salary-In …
         05  Job-Description-In …

WORKING-STORAGE SECTION

Ø       Follows FILE SECTION

Ø       Starts in Area A, ends with period

Ø       All items must be defined at 01 level or in entries subordinate to 01 level entry

Ø       Rules for user-defined data-names apply

Ø       Elementary items:

·         Must include PICTURE clause

·         May be assigned initial value with VALUE clause

LITERALS AND FIGURATIVE CONSTANTS

Ø       Literal is a constant representing a number or Non number (Alpha numeric) like 45.3 / ‘MANAGER’.

Ø       Literals are storable in a memory Location having a user defined name called Data Name or Identifier or Variable or Field

Ø       Figurative Constant is a COBOL RESERVED WORD representing frequently used constants like ZEROS / SPACES.

Ø       Figurative constants are used in the program as such for better readability as.

      MOVE SPACES TO WS-REC.

Ø       Literals are classified in to NUMERIC and NON-NUMERIC literals.

   NUMERIC LITERAL

Ø       Must contain at least one digit

Ø       + or - Sign, if used must be the left-most character

Ø       Not more than one decimal point

Ø       Decimal may not be the right most character

Ø       Maximum of 18 digits.

05  TOTAL-MARK       PIC  9(3)  VALUE   100.

           Here 100 is a numeric constant assigned in identifier TOTAL-MARK.

    NON-NUMERIC LITERAL

Ø       May consist of any character in the character set

Ø       Must be enclosed in quotes

Ø       A numeric literal in quotes is non-numeric

Ø       Maximum length of 120 chars

05   COMPANY-NAME       PIC  X(3)  VALUE   ‘EDS’.

      Here ‘EDS’ is an alphanumeric constant assigned in identifier 

COMPANY-NAME

LIST OF FIGURATIVE CONSTANTS

ZERO / ZEROES / ZEROS          ONE OR MORE ZEROS

QUOTE / QUOTES                    ONE OR MORE “

SPACE / SPACES                     ONE OR MORE SPACE

HIGH-VALUE / HIGH-VALUES   HIGHEST VALUE IN COLLATING  SEQUENCE

X’FF’ FOR EBCDIC

LOW-VALUE / LOW-VALUES  LOWEST VALUE IN COLLATING SEQUENCE

ALL literal                                ONE or MORE OCCURENCES OF litera

Data Description

        The general format of the data description is

Ø       Level-number data-name / FILLER clauses

   LEVEL NUMBERS

Ø          A Record is a Collection of all the fields pertaining to an Item/person/Transaction.

Ø          A record structure is a structure of all the fields of a record. It may be available in the FILE SECTION/ WORKING-STORAGE SECTION/ LINKAGE SECTION.

Ø          The level-number specifies the hierarchy of data within a record, and identifies special-purpose data entries. A level-number begins a data description entry, a renamed or redefined item, or a condition-name entry.

Ø          A level-number has a value taken from the set of integers between 1 and 49, or from one of the special level-numbers, 66, 77, or 88.

          01 This level - number specifies the record itself.

Ø          A level - 01 entry may be either a group item or an elementary item.

Ø          It must begin in Area A.

02-49 These level numbers specify group and elementary items within a record.

Ø          They may begin in Area A or B

Ø          Group Level Data Names Will not have Picture Clause.

      01 EMPLOYEE-REC.

      02 EMP-NO                 PIC    XXXX.

             02 EMP-NAME.

   03  FIRST-NAME     PIC    A(30).

   03  INITIAL-1            PIC    A.

   03  INITIAL-2            PIC    A.

   03  INITIAL-3            PIC    A.

SPECIAL LEVEL NUMBER

66 Identifies items that contain the RENAMES clause.

77 Identifies independent elementar

88 condition nam

Level Number 01 can appear as a Group Level Number as well as Elementary data item level number.

It can appear only as an elementary Data Item Level Number.

Example

01  TOTAL         PIC  9(5).

77  WS-FLAG       PIC  XX.

01  RECORD─I.

    05 DN─1... .                     │<───────────────RECORD─I───────────────>│

    05 DN─2... .                     ┌──────┬──────────┬───────────┬──────────┐

    05 DN─3... .                     │ DN─1 │   DN─2   │   DN─3    │   DN─4   │

    05 DN─4... .                     └──────┴──────────┴───────────┴──────────┘

66  DN─6 RENAMES DN─1 THROUGH DN─3.  │<───────────DN─6────────────>│

  WORKING-STORAGE SECTION.

  01  SWITCHES.

      02 LOADDATA-EOF-SWITCH    PIC X(1) VALUE "N".

         88 LOADDATA-EOF                 VALUE "Y". 

Data Names

Ø       Identifier name/ Data name should not exceed 30 Characters.

Ø       There should be at least one Alphabet anywhere in the name.

Ø       Only special Character allowed is – ( Hyphen) but should not be at the Beginning or End

Ø       Examples of data names

Ø       EMPLOYEE-NAME , COMPANY, 0001AB, 999-EMPLOYEE-RECORD

Ø       Data name must be unique within a Record

Ø       If ‘Name’ is duplicated across Records, it has to be qualified as Identifier-name of Record Name.

·   DISPLAY BALANCE OF STOCK-RECORD

Ø       Here balance is an identifier declared in Stock-record.

Identify the valid data-names

 1.Date-Of-Birth

2. Amount$Out

3. Section

4. My-Section

5.  -First-Name

6.  Last--Name

7.  98-6

8.  Time out

FILLER:

Whenever there is no need for specific reference to fields in a record structure, we name it as

FILLER or F. This Data name is used wherever there is fixed information like SPACES Or Headings

Are stored.

Example     

01 Detail-record.

   05    FILLER     PIC  X(10)   VALUE SPACES.

   05    NAME       PIC  X(30) .

   05    FILLER     PIC  X(10)   VALUE SPACES.
   05    BASIC      PIC  9(05) .

   05    FILLER     PIC  X(10)   VALUE SPACES.
   05    DA         PIC  9(04) .

   05    FILLER     PIC  X(10)   VALUE SPACES.
   05    GROSS      PIC   9(6).