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The DATA DIVISION
Chapter 3
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
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• Must match the files listed in the SELECT
statements
– WORKING-STORAGE SECTION • Defines constants, end-of-file indicators and work
areas • Defines fields not part of input or output files
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
Data-Name Guidelines
1.Use meaningful data-names that describe contents of field• Amount-Due-In instead of A1
2.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)
Defining a Record
• Each FD 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
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
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
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
PICTURE (PIC) clauses
• Specify type of data stored in field• Indicate size of field
Types of data fields
• Alphabetic - A• Only letters or blanks • For name, item description, etc.• Archaic; no longer used
• Alphanumeric - X• Any character - letters, digits, special characters• For an address like 123 N. Main St.
• Numeric - 9• Only digits• For fields used in arithmetic operations
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 9(5).
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
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.
Types of Constants
• Numeric literal• Examples: .05 5280 199.99• Constant used for arithmetic operations
• Nonnumeric (alphanumeric) literal• Examples: “INVALID” “Enter your name”• Constant used for all operations except arithmetic
• Figurative constant• SPACES ZEROS• Reserved word for commonly used values
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 mark
Valid Nonnumeric Literals
'123 Main St.' '$14.99' '12,342' "Enter a value from 1 to 10"
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
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
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• Elementary items:
– Must include PICTURE clause– May be assigned initial value with VALUE
clause
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
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