Cobol application using ODBC or

File processing

Vandana Janeja

CIS 365

With COBOL

OR PowerCobol

ODBC from Control panel\administrative tools

ODBC from control panel\administrative tools

When you create a database in MS.Access be careful not to use COBOL keywords as you will need to access the fields by their name and COBOL will give you an error if it’s a reserved word.

Creating an ODBC DSN name

Creating a form in Power Cobol

Bringing out the control box from power Cobol

Selecting controls to place on the form

Pulling out properties by double clicking the control

Changing properties of the DBAccess control; specifically the DSN name specification

Pulling out the procedure for a control; currently no control is selected so the procedure of the sheet/form will be opened so that we can add global variables

Data Control with the specifications of ODBC(DSN name)

Trapping the click event of the button

Adding the relevant code for database connection buttonSimilarly other code can be added to other buttons.

DBAccess Control

•OPENDB Opens a data source.

•CLOSEDB Closes a data source.

•SELECTRECORDS Select the record group you want to process.

•READNEXTRECORD Reads records one by one from the record group selected by SELECTRECORDS.

•WRITERECORD Adds one record to the table.

•REWRITERECORD Updates a record in the table.

•DELETERECORD Deletes a record in the table.

•COMMITDB Performs commit processing in manual commit mode.

•ROLLBACKDB Performs roll-back processing in manual commit mode.

PUSH1 CLICK event procedure is:

DATA DIVISION.

WORKING-STORAGE SECTION.

PROCEDURE DIVISION.

CALL OPENDB OF ODBC1.

CALL SELECTRECORDS OF ODBC1.

.

.

CALL CLOSEDB OF ODBC1.

PUSH1 CLICK event procedure for writing a record

DATA DIVISION.

WORKING-STORAGE SECTION.

77 WORKNO PIC 9(4).

77 WORKNAME PIC X(32).

77 WORKPHONENO PIC X(64).

PROCEDURE DIVISION.

.

.

.

MOVE WORKNO TO EMPLOYNO OF ODBC1.(OR Move POW-TEXT of Edit1 to Empno of ODBC1)

MOVE WORKNAMETO EMPLOYNAME OF ODBC1.

MOVE WORKPHONENO TO PHONENO OF ODBC1.

CALL WRITERECORD OF ODBC1.

Insert Record Button

For insert the ODBC should not be readOnly: check this in the DBAccess as ff:

V.IMPORTANTReadOnly option should be unchecked if you have to insert records

PUSH1 CLICK event procedure is:

DATA DIVISION.

WORKING-STORAGE SECTION.

77 WORKNO PIC 9(4).

77 TEMPNO PIC 9(4)

PROCEDURE DIVISION.

PERFORM LOOP…………CALL READNEXTRECORD OF ODBC1.

MOVE POW-TEXT OF EDIT1 TO TEMPNO.

MOVE EMPLOYNO OF ODBC1 TO WORKNO.

IF WORKNO = TEMPNO THEN

MOVE "Smith" TO EMPLOYNAME OF ODBC1

MOVE "497-3497" TO PHONENO OF ODBC1

END-IF.

CALL REWRITERECORD OF ODBC1.

Update Record Button

PUSH1 CLICK event procedure is:

DATA DIVISION.

PROCEDURE DIVISION.

.

IF PHONENO OF ODBC1 = "497-3497" THEN

MOVE 1234 TO EMPLOYNO OF ODBC1

MOVE "Brown" TO EMPLOYNAME OF ODBC1

END-IF.

CALL DELETERECORD OF ODBC1.

All records having EMPLOYNO "1234" and EMPLOYNAME "Brown" are deleted.

Delete Record button

Click on run and it will automatically compile and build and link and basically create an exe for you

Click ok to all messages and if there are no errors you should see the output application

Cobol pseudocode / Flowchart for Cobol application

Accept choice from User Insert/Update/Delete

Update ProcessInsert Process Delete Process

Accept choice from User Insert/Update/Delete

While ChoiceNot Exit

IF choice =“I” INSERTION

IF choice=“D” DELETION

IF choice=“U” UPDATING

IF choice=“P” PRINTMODULE

Else Exit.

INSERTION

Accept Working or temporary variables

Check If record exists

If not Insert

File opening mode I-O ,Read file first for searching the record.Once not found use the “ Write “ verbElse display a message that record already exists

Accept Working or temporary variables

Check If record exists

If yes Update Old record with New Record

Use REWRITE EMPLOYEE-RECORD

UPDATING

Accept Working or temporary variables

Check If record exists

If yes Delete

• Create a New file without the deleted record

• Have an additional field which can be set to “D” for a deleted record, and this file can be periodically renewed.

DELETION

PRINTMODULE

Printing a Report.

• A report is made up of groups of printed lines of different types.

• What types of line are required for the Student Details Report?

The report, will be based on the Data FileThe report, will be based on the Data File

The report will show the details of the records of The report will show the details of the records of studentsstudents

Report Print Lines.

• Page Heading.

– UL Student Details Report

• Page Footing.

– Page : PageNum

• Column Headings.

– Student Id. Student Name Gender Course

• Student Detail Line.

– StudentId. StudentName Gender CourseCode

• Report Footing.

– *** End of Student Details Report ***

Describing Print Lines.

01 PageHeading. 02 FILLER PIC X(7) VALUE SPACES. 02 FILLER PIC X(25) VALUE "UL Student Details Report".

01 PageFooting. 02 FILLER PIC X(19) VALUE SPACES. 02 FILLER PIC X(7) VALUE "Page : ". 02 FILLER PIC 99.

01 ColumnHeadings PIC X(36) VALUE " StudentId StudentName Gender Course".

01 StudentDetailLine. 02 PrnStudId PIC BB9(7). 02 PrnStudName PIC BBX(10). 02 PrnGender PIC BBBBX. 02 PrnCourse PIC BBBBX(4).

01 ReportFooting PIC X(38) VALUE "*** End of Student Details Report ***".

• The Print Lines are all different record types!

The File Buffer

• All data coming from, or going to, the peripherals must pass through a file buffer declared in the File Section.

• The file buffer is associated with the physical device by means of a Select and Assign clause.

• In previous lectures we saw that the file bufferis represented by a record description (01 level).

• But the different types of line that must appear on our report are declared as different record types.

• How can we declare these different record types in the File Section?

ENVIRONMENT DIVISION.INPUT-OUTPUT SECTION.FILE-CONTROL. SELECT Printer ASSIGN TO “LPT1”.

DATA DIVISION.FILE SECTION.FD Printer.01 PrintLine. ????????????????

No VALUE clause in the FILE SECTION.

• Defining a file buffer which is used by different record types is easy (as we have seen).

But !!

• These record types all map on to the same area of storage and print line records cannot share the same area of storage.

• Why? Because most of the print line record values are assigned using the VALUE clause and these values are assigned as soon as the program starts.

• To prevent us trying to use the VALUE clause to assign values to a File buffer COBOL has a rule which states that;

In the FILE SECTION, the VALUE clause must be used in condition-name entries only (i.e. it cannot be used

to give an initial value to an item).

A Solution

• We define the print records in the WORKING-

STORAGE SECTION.• We create a file buffer in the FILE SECTION

which is the size of the largest print record.• We print a line by moving the appropriate print

record to the file buffer and then WRITEing the contents of the file buffer to the device.

We get round the problem as follows;We get round the problem as follows;

ENVIRONMENT DIVISION.INPUT-OUTPUT SECTION.FILE-CONTROL. SELECT ReportFile ASSIGN TO “STUDENTS.RPT”.

DATA DIVISION.FILE SECTION.FD ReportFile.01 PrintLine PIC X(38).

WORKING-STORAGE SECTION.01 PageHeading. 02 FILLER PIC X(7) VALUE SPACES. 02 FILLER PIC X(25) VALUE "UL Student Details Report".

01 PageFooting. 02 FILLER PIC X(19) VALUE SPACES. 02 FILLER PIC X(7) VALUE "Page : ". 02 FILLER PIC 99.

01 ColumnHeadings PIC X(36) VALUE " StudentId StudentName Gender Course".

01 StudentDetailLine. 02 PrnStudId PIC BB9(7). 02 PrnStudName PIC BBX(10). 02 PrnGender PIC BBBBX. 02 PrnCourse PIC BBBBX(4).

01 ReportFooting PIC X(38) VALUE "*** End of Student Details Report ***".

STUDENTS.RPT

DISK

WRITE Syntax revisited.

• When we are writing to a printer or a print file we use a form of the WRITE command different from that we use when writing to a sequential file.

LINES

LINE

AFTER

BEFORE

Identifier FROM RecordName

PAGE

meMnemonicNa

AdvanceNum

ADVANCING

WRITE

ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT ReportFile ASSIGN TO "STUDENTS.RPT" ORGANIZATION IS LINE SEQUENTIAL.

DATA DIVISION. FILE SECTION. FD ReportFile. 01 PrintLine PIC X(40).

WORKING-STORAGE SECTION. 01 HeadingLine PIC X(21) VALUE " Record Count Report".

01 StudentTotalLine. 02 FILLER PIC X(17) VALUE "Total Students = ". 02 PrnStudentCount PIC Z,ZZ9.

01 MaleTotalLine. 02 FILLER PIC X(17) VALUE "Total Males = ". 02 PrnMaleCount PIC Z,ZZ9.

01 FemaleTotalLine. 02 FILLER PIC X(17) VALUE "Total Females = ". 02 PrnFemaleCount PIC Z,ZZ9.

MOVE StudentCount TO PrnStudentCountMOVE MaleCount TO PrnMaleCountMOVE FemaleCount TO PrnFemaleCountWRITE PrintLine FROM HeadingLine AFTER ADVANCING PAGEWRITE PrintLine FROM StudentTotalLine AFTER ADVANCING 2 LINESWRITE PrintLine FROM MaleTotalLine AFTER ADVANCING 2 LINESWRITE PrintLine FROM FemaleTotalLine AFTER ADVANCING 2 LINES.

STUDENTS.RPT

DISK