PROGRAM-ID. PROGRAM1 AS "WEEK13___RANDOMSEQUENTIAL.PROGRAM1".

       ENVIRONMENT DIVISION.

       INPUT-OUTPUT SECTION.

       FILE-CONTROL.

       SELECT CUSTOMER-INPUT-FILE ASSIGN TO
           "C:\USERS\BWOOD\DOCUMENTS\COBOL\WEEK13_INPUT.DAT"
               ORGANIZATION IS LINE SEQUENTIAL.

       SELECT CUSTOMER-MASTER-FILE ASSIGN TO
           "C:\USERS\BWOOD\DOCUMENTS\COBOL\WEEK13_MASTER.DAT"
               ORGANIZATION IS INDEXED
               ACCESS IS RANDOM RECORD KEY IS MASTER-CUSTOMER-NO.

       SELECT CUSTOMER-MASTER-DISPLAY-FILE ASSIGN TO
           "C:\USERS\BWOOD\DOCUMENTS\COBOL\WEEK13_MASTER.DAT"
               ORGANIZATION IS INDEXED
               ACCESS IS SEQUENTIAL
               RECORD KEY IS DISPLAY-CUSTOMER-NO.

       DATA DIVISION.

       FD CUSTOMER-INPUT-FILE.
       01 INPUT-RECORD.
           05 CUSTOMER-NO              PIC A(5).
           05 CUSTOMER-NAME            PIC A(20).
           05 DATE-OF-PURCHASE.
               10 DATE-OF-PURCHASE-M   PIC 9(2).
               10 DATE-OF-PURCHASE-D   PIC 9(2).
               10 DATE-OF-PURCHASE-Y   PIC 9(4).
           05 AMT-OF-PURCHASE          PIC 9(5).

       FD CUSTOMER-MASTER-FILE.
       01 MASTER-REC-IO.
           05 MASTER-CUSTOMER-NO       PIC A(5).
           05 MASTER-CUSTOMER-NAME     PIC A(20).
           05 MASTER-DATE-OF-LAST-PURCHASE.
               10 MASTER-DATE-OF-PURCHASE-M   PIC 9(2).
               10 MASTER-DATE-OF-PURCHASE-D   PIC 9(2).
               10 MASTER-DATE-OF-PURCHASE-Y   PIC 9(4).
           05 MASTER-AMOUNT-OWED       PIC 9(6).

       FD CUSTOMER-MASTER-DISPLAY-FILE.
       01 DISPLAY-REC.
           05 DISPLAY-CUSTOMER-NO       PIC A(5).
           05 DISPLAY-CUSTOMER-NAME     PIC A(20).
           05 DISPLAY-DATE-OF-LAST-PURCHASE.
               10 DISPLAY-DATE-OF-PURCHASE-M   PIC 9(2).
               10 DISPLAY-DATE-OF-PURCHASE-D   PIC 9(2).
               10 DISPLAY-DATE-OF-PURCHASE-Y   PIC 9(4).
           05 DISPLAY-AMOUNT-OWED       PIC 9(6).

       WORKING-STORAGE SECTION.

       01 WORK-AREA.
           05 ARE-THERE-MORE-RECORDS   PIC X(1) VALUE "Y".
               88 NO-MORE-RECORDS               VALUE "N".

       PROCEDURE DIVISION.

       100-MAIN.

           OPEN INPUT CUSTOMER-INPUT-FILE
           OPEN I-O CUSTOMER-MASTER-FILE

           PERFORM UNTIL NO-MORE-RECORDS
               READ CUSTOMER-INPUT-FILE
                   AT END
                       MOVE "N" TO ARE-THERE-MORE-RECORDS
                   NOT AT END
                       PERFORM 200-CALC
               END-READ
           END-PERFORM

           CLOSE CUSTOMER-INPUT-FILE
           CLOSE CUSTOMER-MASTER-FILE

           PERFORM 500-SHOW-MASTER-FILE

           STOP RUN.

       200-CALC.

           MOVE SPACES TO MASTER-REC-IO
           MOVE CUSTOMER-NO TO MASTER-CUSTOMER-NO
           READ CUSTOMER-MASTER-FILE
               INVALID KEY PERFORM 700-INSERT-REC
               NOT INVALID KEY PERFORM 800-UPDATE-REC
           END-READ.

       500-SHOW-MASTER-FILE.

           OPEN INPUT CUSTOMER-MASTER-DISPLAY-FILE

           MOVE "Y" TO ARE-THERE-MORE-RECORDS
           PERFORM UNTIL NO-MORE-RECORDS
               READ CUSTOMER-MASTER-DISPLAY-FILE
                   AT END
                       MOVE "N" TO ARE-THERE-MORE-RECORDS
                   NOT AT END
                       DISPLAY DISPLAY-CUSTOMER-NO & " " & DISPLAY-CUSTOMER-NAME & " " &
                           DISPLAY-DATE-OF-LAST-PURCHASE & " " & DISPLAY-AMOUNT-OWED
               END-READ
           END-PERFORM

           CLOSE CUSTOMER-MASTER-DISPLAY-FILE.


       700-INSERT-REC.

           MOVE CUSTOMER-NO TO MASTER-CUSTOMER-NO
           MOVE CUSTOMER-NAME TO MASTER-CUSTOMER-NAME
           MOVE DATE-OF-PURCHASE TO MASTER-DATE-OF-LAST-PURCHASE
           MOVE AMT-OF-PURCHASE TO MASTER-AMOUNT-OWED

           WRITE MASTER-REC-IO
               INVALID KEY DISPLAY "ERROR INSERTING RECORD" & CUSTOMER-NO
               NOT INVALID KEY DISPLAY "INSERTED CUSTOMER " & CUSTOMER-NO
           END-WRITE.

       800-UPDATE-REC.

           MOVE CUSTOMER-NO TO MASTER-CUSTOMER-NO
           MOVE CUSTOMER-NAME TO MASTER-CUSTOMER-NAME
           MOVE DATE-OF-PURCHASE TO MASTER-DATE-OF-LAST-PURCHASE
           ADD AMT-OF-PURCHASE TO MASTER-AMOUNT-OWED

           REWRITE MASTER-REC-IO
               INVALID KEY DISPLAY "ERROR UPDATING RECORD" & CUSTOMER-NO
               NOT INVALID KEY DISPLAY "UPDATED CUSTOMER " & CUSTOMER-NO
           END-REWRITE.

       END PROGRAM PROGRAM1.