Any Questions!

Agenda

• Fun with Functions • Externally Described Files• Condition Names• Iteration• Logical Files• Random Reads

Fun with Functions

ILEFUNCT

Condition Names

• Used with Code Fields– Eg. ARE-THERE-MORE-RECORDS– Eg. FINAL-GRADE– Eg. Indicators

Condition Names01 ARE-THERE-MORE-RECORDS PIC X(3) VALUE ‘YES’.

88 THERE-ARE-MORE-RECORDS VALUE ‘YES’.88 END-OF-FILE VALUE ‘NO’.

IF THERE-ARE-MORE-RECORDSREAD EMPLOYEE-FILE.

IF END-OF-FILEPERFORM TERMINATION-RTN.

Set Verb

• Used to initialize fields to a Condition-Name.01 ARE-THERE-MORE-RECORDS PIC X(3).

88 THERE-ARE-MORE-RECORDS VALUE ‘YES’.88 END-OF-FILE VALUE ‘NO’.

SET END-OF-FILE TO TRUE.

Conditions Cont’d01 WORK-DAYS PIC X(3).

88 MONDAY VALUE ‘MON’.88 TUESDAY VALUE ‘TUE’.88 WEDNESDAY VALUE ‘WED’.88 THURSDAY VALUE ‘THU’88 FRIDAY VALUE ‘FRI’.

SET MONDAY TO TRUE.IF FRIDAY

DISPLAY ‘GO HOME EARLY’.

Conditions Cont’d01 FALL-MONTHS PIC X(3).

88 SEPTEMBER VALUE ‘SEP’.88 OCTOBER VALUE ‘OCT’.88 NOVEMBER VALUE ‘NOV’.88 DECEMBER VALUE ‘DEC’.

IF OCTOBERDISPLAY ‘HAPPY HALLOWEEN!!’

SET DECEMBER TO TRUE.

Option Indicators and Conditions01 WS-indicators.

05 IN90 INDICATOR 90 PIC 1.88 display-message value B’1’.88 dont-display-message value B’0’.

Set display-message to true.Set dont-display-message to true.If display-messageIf don’t-display-messageIf not display-message

Response Indicators and Conditions

01 WS-Control.05 ws-function-key pic x(2).

88 F3 value ’03’88 F12 value ’12’.88 Enter value ’00’

05 ws-device-name pic x(10).05 ws-record-format pic x(10).

If F3If not F3

Iteration

Looping

BASIC Perform Statement

PERFORM (paragraph-name)

Basic PERFORM

READ Emp-FilePERFORM DSP-RtnSTOP RUN

DSP-RTNmove emp-in to emp-out.

write dsp-record format is ‘SCREEN’. read dsp-file record.

PERFORM Until

PERFORM paragraph-nameUNTIL Condition

PERFORM Until

ConditionMet?

Execute Program

Statements

NO

YES

PERFORM Until

READ Emp-File AT END Move ‘YES’ TO EOF.

PERFORM Dsp-Rtn UNTIL EOF = ‘Y’

STOP RUN

DSP-RTNmove emp-in to emp-out.write dsp-record

format is ‘SCREEN’. read dsp-file RECORD. read emp-file

at endmove ‘YES’ to EOF.

PERFORM X Times

PERFORM (paragraph-name) THROUGH/THRU (paragraph-name)(integer/variable) TIMES

PERFORM X Times

Number ofTimes Met?

Execute Program

Statements

NO

YES

PERFORM X Times

READ Emp-File AT END Move ‘YES’ TO EOF.

PERFORM Dsp-Rtn 5 TIMES

STOP RUN

DSP-RTNmove emp-in to emp-out.write dsp-record

format is ‘SCREEN’.

read dsp-file record.

PERFORM With Test After

PERFORM (paragraph-name) THROUGH/THRU (paragraph-name)WITH TEST AFTERUNTIL Condition

PERFORM With Test After

Condition Met?

Execute Program

Statements

NO

YES

PERFORM With Test After

READ Emp-File AT END Move ‘YES’ TO EOF.

PERFORM Dsp-Rtn WITH TEST AFTERUNTIL EOF = ‘Y’

STOP RUN

DSP-RTNmove emp-in to emp-out.

write dsp-record format is ‘SCREEN’. read dsp-file record. read emp-file

AT ENDMOVE ‘YES’ TO

EOF.

PERFORMs within PERFORMs

READ Emp-File AT END Move ‘YES’ TO EOF.

PERFORM DSP-Rtn UNTIL 5 TIMES

STOP RUN

DSP-RTNMOVE EMP-IN TO EMP-OUT.PERFORM Write-Rtn

Iteration Statement to Use?

• Perform Until– Tests for the condition first– Statements are executed only if the condition is

true• Perform With Test After

– tests for the condition last– Statements are always executed at least once

Iteration Statement to Use?

• Perform X Times– Use this when you know the number of times

the paragraph(s) are to be executed.

Sorting Data

Using Access Paths

Physical Files vs Logical Files

EMPLOYEEPF *FILE

EMPLOYEE *FILE

Physical Files or Logical Files?

Externally Described Files

• Select Statement when physical/logical file has a key.

SELECT Cobol-file-nameASSIGN TO database-actual-file-name[ORGANIZATION IS INDEXED][ACCESS MODE IS SEQUENTIAL] RECORD KEY is data-element.(data-element could be EXTERNaLLY-DESCRIBED-KEY)

Externally Described Files

• Copying the record layout.

FD Cobol-file-name.01 Cobol-Record-Name.COPY DD-actualrecordname OF actualfilename.

(DD can be replaced by DDS if you require the 10 char field names instead of the aliases)

Handy Physical File Commands

DSPPFM – Display Physical File MemberDisplays the contents of a Physical File in arrival sequence.

DSPFD – Display File DescriptionInformation about the file – eg access path.

DSPFFD – Display File Field DescriptionDisplays the fields in the file.

Random Reads

• Used to retrieve a record based on the value of a key field

• Need an access path sorted by the key field needed

• Select statement changes

Defining a Random Access File

SELECT Employee-FileASSIGN to DATABASE-EMPPFORGANIZATION is INDEXEDACCESS MODE is RANDOMRECORD KEY is

EXTERNALLY-DESCRIBED-KEY(with duplicates).

Random Reads• If the key field to EMPPF is the Employee-

Number then:Move 1 to Employee-Number.Read Employee-File

Invalid KeyMove ‘Error’ to Employee-Name-Out

Not invalid key Move Employee-Name to Employee-Name-

outEnd-Read.

Validating the Province Code

Database object: PROVINCES