Indexed Files continued

Figure 17.1 Sequential Update

OLD MASTER

TRANSACTION

NEWMASTER

ERRORMESSAGES

UPDATEPROGRAM

Figure 17.2 Sequential Update with Data Files

ERROR MESSAGES:

NO MATCH 500000000DUPLICATE ADDITION 888888888

SEQUENTIALUPDATE

OLD MASTER FILE:

111111111ADAMS 015000 NEW YORK222222222BAKER 025000 NEW YORK333333333ZIDROW 008000 NEW YORK444444444MILGROM 040000 BOSTON555555555BENJAMIN 100000 CHICAGO666666666SHERRY 007500 CHICAGO777777777BOROW 017500 BOSTON888888888JAMES 050000 NEW YORK 999999999RENAZEV 030000 NEW YORK

TRANSACTION FILE:

222222222 028000 C222222222 BOSTON C400000000NEW EMPLOYEE 016000 BOSTON A500000000 020000 C610000000NEW EMPLOYEE II 018000 CHICAGO A610000000 NEW YORK C 666666666SHERRY D777777777 055000 C888888888JAMES 017500 NEW YORK A

NEW MASTER FILE:

111111111ADAMS 015000 NEW YORK222222222BAKER 025000 NEW YORK333333333ZIDROW 008000 NEW YORK444444444MILGROM 040000 BOSTON 400000000NEW EMPLOYEE 016000 BOSTON 555555555BENJAMIN 100000 CHICAGO 610000000NEW EMPLOYEE II 018000 NEW YORK666666666SHERRY 007500 CHICAGO777777777BOROW 017500 NEW YORK888888888JAMES 050000 NEW YORK999999999RENAZEV 030000 NEW YORK

Figure 17.4 Sequential Update with Data Validation

TRANSACTIONFILE

OLD MASTER

STEP 1: EDIT

NEW MASTER

STEP 2: UPDATEVALID

TRANSACTIONS

ERRORMESSAGESERROR

MESSAGES

Figure 17.3 Two-period Sequential Update

MASTERAS OF 1/1

JANUARYTRANSACTIONS

MASTERAS OF 2/1

UPDATEPROGRAM

MASTERAS OF 3/1

UPDATEPROGRAM

FEBRUARYTRANSACTIONS

Processing done February 1

Processing done March 1

Figure 17.7 Pseudocode for Data Validation Program

Open filesDO while data remains READ transaction file AT END

Indicate no more data NOT AT END

Move ‘YES’ to valid-record-switchIF trans-social-security < previous-social-security Move ‘NO’ to valid-record-switch Write error messageENDIFMove trans-social-security to previous-social-securityIF transaction-code is not valid Move ‘NO’ to valid-record-switch Write error messageENDIFIF addition IF transactions fails addition-check(s) Move ‘NO’ to valid-record-switch

Write error message(s) ENDIFELSE IF correction IF sales-amount not numeric

Move ‘NO’ to valid-record-switch Write error message ENDIF ENDIFENDIFIF valid-record-switch = ‘YES’ Write valid-transaction-recordENDIF

ENDREADENDDOClose filesStop run

Figure 18.4 Pseudocode for Creating Indexed File

Open filesDO WHILE data remains READ record from sequential file

AT END Indicate no more dataNOT AT END Move sequential record to indexed record Write indexed record IF sequence error

Display error - record out of sequence ENDIF IF duplicate record

Display error - record already exists ENDIF

ENDREADENDDOClose filesStop run

READINDEXED F ILE

ADD NEWRECO RD

CO RRECTEXISTINGRECO RD

DELETE EXISTINGRECO RD

APPLYTRANS TOMASTER

PRO CESSTRANSACTIO N

F ILE

Figure 18.8 Hierarchy Chart for Nonsequential Update Program

Figure 18.9 Pseudocode for Nonsequential Update ProgramOpen files

DO WHILE data remains READ transaction file

AT END Indicate no more dataNOT AT END Move transaction social security number to record key READ INDEXEC-FILE INVALID KEY

Move ‘NO’ TO record-key-allocated-switch NOT INVALID KEY

Move ‘YES’ TO record-key-allocated-switch END-READ EVALUATE WHEN addition

IF record-key-allocated-switch = ‘YES’ Write ‘error - duplicate addition’ELSE (transaction is not in indexed file) Move transaction-record to new-master-record Write indexed-recordENDIF

WHEN correctionIF record-key-allocated-switch = ‘YES’ Process correction Rewrite indexed recordELSE (transaction is not in indexed file) Write ‘error - no matching record’ENDIF

WHEN deletionIF record-key-allocated-switch = ‘YES’ Delete indexed recordELSE (transaction is not in indexed file) Write ‘error - no matching record’ENDIF

WHEN otherWrite ‘error - invalid transaction’

END EVALUATE END READEND DOClose FilesStop Run

• The START Statement– Start Filename Key Relational Operator – Invalid Key Statement– Not Invalid Key Statement– End-Start

• Read Next– Read Filename Next Record– At End Statement– End-Read

• File Status (Select Filename File Status is WS-STATUS)– Refer to pages 484 - 485)