Random update

1. Random update Please use speaker notes for additional information!

2. Update Random Update • EDIT: The transactions that will be used in the update must be as error free as possible to prevent corrupting the master file. To assure the integrity of the data, the transactions can be processed in an edit program and only valid transactions should be allowed to update the master file. The output of the edit file includes the valid (good) transaction file which will be processed in the next step. Frequently transaction come in via a screen and the analyst decides that the editing will be incorporated in the update program to provide interactivity. • UPDATE:The update program uses the valid transaction file to update the master file itself. No new master file is created, the changes are made to the existing master file. Note that random updating is transaction driven. This means that you read the transaction file and find the master that needs to be updated. When you have processed all of the transactions, the processing is done. Reports become extremely important to provide a paper trail of records processed and also a trail of records that contained errors and were not processed. In a maintenance update there can be add, change or delete transactions so records can be added to the existing master, changed on the existing master, or deleted from the existing master. The method of physically handling deletes varies depending on technology being used.. The update program completes the updating maintenance cycle. Note that back up does not happen automatically in a random update. Copies of the master file and the transaction file need to be made. Frequently the master is backed up directly after the update. It absolutely has to be backed up before the next update.

3. Systems flowchart Valid Trans Update Program Data Edit Program Errors Errors can be put on disk, printed, interactively corrected or any combination of solutions. Master File Trail Note: Errors can be written to disk, printed, interactively corrected or any combination of solutions. An optional paper trail can also be produced on disk, paper or another medium.

4. Random Update Screen Transactions OR Transactions Master Random Update Program If transactions are coming in as a group from a disk file, they should be edited. If the transactions are coming from a screen, interactive editing should take place in the Random Update Program. The user will frequently try to interactively handle errors on the screen. Errors Trail

5. Random Update Logic

6. readTrans process start Read a transaction housekeeping readTrans Y end-readTrans process not EOF loop N wrapup end-process readMstr stop read master housekeeping wrapup Y N successful open files close files success not success end-housekeeping end-wrapup end-readMstr

7. loop establish key read mstr Y N success N change trans Y Y N add trans N delete trans change routine Y Y add routine N change trans add error routine delete routine rewrite master write master delete error routine change error routine delete master readTran end -loop

8. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D 999... MASTER (after) 121... 123… 222... 234… 333... 345… 444... 456… 512… 121 (trail) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. If a match is found, changes are made to the record on the master and the record is put back on the master with a REWRITE. A trail of the change is also made.

9. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D 999... MASTER (after) 121... 123… 124... 222... 234… 333... 345… 444... 456… 512… 121 (trail) 124 (trail) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since no match is found and this is an add, the new record is written on the Master using a WRITE. A trail of the add is also made.

10. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D 999... MASTER (after) 121... 123… 124... 222... 234… 333... 345… 444... 456… 512… 121 (trail) 124 (trail) 222 (trail) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since a match is found and this is a change, the change is made and the changed Master replaces the original record on the master using the REWRITE. A trail of the change is also made.

11. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D 999... MASTER (after) 121... 123… 124... 222... 234… 333... 345… 444... 456… 512… 121 (trail) 124 (trail) 222 (trail) 222 (trail) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since a match is found and this is a change, the change is made and the changed Master replaces the original record on the master using the REWRITE. A trail of the change is also made.

12. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D 999... MASTER (after) 121... 123… 124... 222... 234… 345… 444... 456… 512… 121 (trail) 124 (trail) 222 (trail) 222 (trail) 333 (trail) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since a match is found and this is an delete, the delete is made by removing the record from the Master using the DELETE verb. A trail of the delete is also made.

13. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D 999... MASTER (after) 121... 123… 124... 222... 234… 345… 444... 456… 512… 121 (trail) 124 (trail) 222 (trail) 222 (trail) 333 (trail) 350 (error) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since no match is found and this is a change, no change is made to the master. A report of the change error is also made.

14. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D MASTER (after) 121... 123… 124... 222... 234… 345… 444... 456… 512… 121 (trail) 124 (trail) 222 (trail) 222 (trail) 333 (trail) 350 (error) 444 (error) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since a match is found and this is a add, no change is made to the master. A report of the add error is also made.

15. Random Update ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 121… C 124… A 222… C 222… C 333… D 350… C 444… A 450… D MASTER (after) 121... 123… 124... 222... 234… 345… 444... 456… 512… 121 (trail) 124 (trail) 222 (trail) 222 (trail) 333 (trail) 350 (error) 444 (error) 450 (error) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since no match is found and this is a delete, no change is made to the master. A report of the delete error is also made.

16. Random Update with unsorted transactions MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 350… C 222… C 124… A 450… D 333… D 121… C 444… A 222… C 999... MASTER (after) 121... 123… 222... 234… 333... 345… 444... 456… 512… 350 (error) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since no match is found and this is a change, no change is made to the master. A report of the change error is also made.

17. Random Update with unsorted transations ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 350… C 222… C 124… A 450… D 333… D 121… C 444… A 222… C 999... MASTER (after) 121... 123… 124... 222... 234… 333... 345… 444... 456… 512… 350 (error) 222 (trail) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since a match is found and this is a change, the change is made and the changed Master replaces the original record on the master using the REWRITE. A trail of the change is also made.

18. Random Update with unsorted transactions ERROR /TRAIL REPORT MASTER (before) 121... 123… 222... 234… 333... 345… 444... 456… 512… TRANSACTIONS 350… C 222… C 124… A 450… D 333… D 121… C 444… A 222… C 999... MASTER (after) 121... 123… 124... 222... 234… 333... 345… 444... 456… 512… 350 (error) 222 (trail) 124 (trail) The transaction is read and then there is an attempt made to find the matching record identification number on the Master. Since no match is found and this is an add, the new record is written on the Master using a WRITE. A trail of the add is also made.