Data Division, Data Fields, and PICTURE Clauses

Learning goals

After studying this lesson, learners should be able to:

1. Form valid COBOL data names.
2. Explain files, records, and fields.
3. Distinguish numeric, alphabetic, and alphanumeric data fields.
4. Use the File Section and Working-Storage Section.
5. Apply common PIC characters and editing characters.

Naming rules for data names

A COBOL data name should:

• Use letters, digits, and hyphens only.
• Avoid embedded spaces.
• Contain at least one letter.
• Not begin or end with a hyphen.
• Not be a reserved word.
• Be meaningful and specific.

Good examples:

STUDENT-NO
STUDENT-NAME
TOTAL-SALES
NET-PAY
EOF-SW

Weak examples:

A1        too vague
SID       unclear abbreviation
JOHN      person-specific and not descriptive
TOTAL     too broad if several totals exist

Variable data and constant data

COBOL programs use both changing and fixed data.

Data organization: file, record, field

Business programs usually organize data in layers:

1. File - a collection of related records.
2. Record - one complete unit inside a file, such as one student or one employee.
3. Field - one piece of data inside a record, such as name, ID number, or grade.

Example:

File: STUDENT-FILE
Record: STUDENT-RECORD
Fields: STUDENT-NO, STUDENT-NAME, MIDTERM-GRADE, FINAL-GRADE

Types of data fields

COBOL commonly uses three field categories:

Examples:

05  STUDENT-NAME     PIC X(30).
05  AGE              PIC 99.
05  SECTION-CODE     PIC X(10).
05  LAST-NAME        PIC A(20).

Numeric literals

Rules for numeric literals:

• Use digits 0 through 9.
• Do not use commas in the stored numeric literal.
• A sign may appear on the left, such as -125 or +50.
• A decimal point may appear inside a numeric literal but not as the final character.

Examples:

Group and elementary fields

A group field contains smaller fields. An elementary field cannot be subdivided further.

Example:

01  STUDENT-RECORD.
    05 STUDENT-NO        PIC X(10).
    05 STUDENT-NAME.
       10 LAST-NAME      PIC X(15).
       10 FIRST-NAME     PIC X(15).
       10 MIDDLE-INITIAL PIC X.
    05 FINAL-GRADE       PIC 9V99.

Here, STUDENT-RECORD and STUDENT-NAME are group items. STUDENT-NO, LAST-NAME, FIRST-NAME, MIDDLE-INITIAL, and FINAL-GRADE are elementary items.

Data Division structure

A common Data Division contains two major sections:

       DATA DIVISION.
       FILE SECTION.
       FD  file-name.
       01  record-name.
           05 field-name PIC clause.

       WORKING-STORAGE SECTION.
       01  variable-name PIC clause VALUE initial-value.

File Section

The File Section describes input and output files and their records.

       FILE SECTION.
       FD  STUDENT-FILE
           LABEL RECORD IS STANDARD
           RECORD CONTAINS 41 CHARACTERS
           DATA RECORD IS STUDENT-RECORD.
       01  STUDENT-RECORD.
           05 STUDENT-NO      PIC X(10).
           05 STUDENT-NAME    PIC X(25).
           05 MIDTERM-GRADE   PIC 9V99.
           05 FINAL-GRADE     PIC 9V99.

Common File Description entries:

Working-Storage Section

The Working-Storage Section stores variables, counters, switches, report headings, and intermediate results that are not directly part of an input file.

       WORKING-STORAGE SECTION.
       01  EOF-SW             PIC 9 VALUE 0.
       01  RECORD-COUNT       PIC 9(4) VALUE 0.
       01  TOTAL-GRADE        PIC 9(5)V99 VALUE 0.
       01  AVERAGE-GRADE      PIC 9V99 VALUE 0.

Common uses:

• Counters
• Totals
• End-of-file switches
• Report headings
• Display/output formatting fields
• Temporary calculation storage

PICTURE clause

The PICTURE or PIC clause defines the type and size of an elementary data item.

05  CUSTOMER-NAME     PIC X(30).
05  QUANTITY          PIC 9(3).
05  PRICE             PIC 9(5)V99.

Rules:

• A group item should not have a PIC clause.
• An elementary item normally needs a PIC clause.
• PIC 9999 and PIC 9(4) mean the same thing.
• Numeric fields used in arithmetic should use 9, not X.

Common PICTURE characters

Assumed decimal point with V

The V character marks a decimal location without storing an actual decimal point.

FILLER

FILLER reserves positions that do not need a unique name.

Example:

01  PRINT-LINE.
    05 FILLER       PIC X(10) VALUE SPACES.
    05 PRINT-NAME   PIC X(25).
    05 FILLER       PIC X(5)  VALUE SPACES.
    05 PRINT-GRADE  PIC ZZ9.99.

Use FILLER for spacing, labels, or unused areas in report records.

VALUE clause

The VALUE clause gives an initial value to a Working-Storage item.

05  WS-DISCOUNT        PIC V99 VALUE .15.
05  WS-LAB-FEE         PIC 9(3) VALUE 350.
05  WS-MORE-RECORDS    PIC X(3) VALUE "YES".
05  WS-TITLE           PIC X(14) VALUE "MONTHLY REPORT".

Data editing

Data editing formats values for output. It is usually done by moving a raw numeric value into an edited field.

Common editing symbols:

Examples:

05  AMOUNT-IN       PIC 9(5)V99 VALUE 0250025.
05  AMOUNT-OUT      PIC ZZ,ZZ9.99.

05  DATE-IN         PIC 9(6) VALUE 011591.
05  DATE-OUT        PIC 99/99/99.

After moving DATE-IN to DATE-OUT, the displayed date is formatted as 01/15/91.