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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 Bringing out the control box from power Cobol Creating a form in 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 Data Control with the specifications of Pulling out the procedure for a ODBC(DSN name) control; currently no control is selected so the procedure of the sheet/form will be opened so that we can add global variables Trapping the click event of the button Adding the relevant code for database connection button Similarly 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). Insert Record Button 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 WORKNAME TO EMPLOYNAME OF ODBC1. MOVE WORKPHONENO TO PHONENO OF ODBC1. CALL WRITERECORD OF ODBC1. For insert the ODBC should not be readOnly: check this in the DBAccess as ff: V.IMPORTANT ReadOnly option should be unchecked if you have to insert records PUSH1 CLICK event procedure is: Update Record Button 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. PUSH1 CLICK event procedure is: DATA DIVISION. Delete Record button 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. 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 While Choice Not Exit Insert Process Update Process Delete Process Accept choice from User Insert/Update/Delete 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 “ verb Else display a message that record already exists UPDATING Accept Working or temporary variables Check If record exists If yes Update Old record with New Record Use REWRITE EMPLOYEE-RECORD DELETION 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. PRINTMODULE Printing a Report. The report, will be based on the Data File The report will show the details of the records of students • A report is made up of groups of printed lines of different types. • What types of line are required for the Student Details Report? 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. ENVIRONMENT DIVISION. • The file buffer is associated INPUT-OUTPUT SECTION. with the physical device by FILE-CONTROL. SELECT Printer means of a Select and ASSIGN TO “LPT1”. Assign clause. DATA DIVISION. • In previous FILE SECTION. FD Printer. lectures we saw 01 PrintLine. ???????????????? that the file buffer is 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? 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 get round the problem as follows; • 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. 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. DISK 01 PageHeading. 02 FILLER PIC X(7) VALUE SPACES. STUDENTS.RPT 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 ***". 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. WRITE RecordName FROM Identifier LINE AdvanceNum LINES BEFORE AFTER ADVANCING MnemonicName PAGE ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT ReportFile ASSIGN TO "STUDENTS.RPT" ORGANIZATION IS LINE SEQUENTIAL. DATA DIVISION. DISK FILE SECTION. FD ReportFile. 01 PrintLine PIC X(40). STUDENTS.RPT 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 PrnStudentCount MOVE MaleCount TO PrnMaleCount MOVE FemaleCount TO PrnFemaleCount WRITE PrintLine FROM HeadingLine AFTER ADVANCING PAGE WRITE PrintLine FROM StudentTotalLine AFTER ADVANCING 2 LINES WRITE PrintLine FROM MaleTotalLine AFTER ADVANCING 2 LINES WRITE PrintLine FROM FemaleTotalLine AFTER ADVANCING 2 LINES.
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