Re: Subfile Processing

When the user edits one of the displayed subfile records and hits enter I
attempt to save it back to the correct file using a DOW to loop through
each record returned from the subfile using READC(E) until I get an %EOF. 
In this loop I use a KLIST to search using SETLL(E) on the physical file
to find the corresponding entry to the subfile entry I'm working on.  If I
get an %EQUAL result then I know it's an update to an existing record in
the physical file so I use UPDATE(E) to write it out.  Otherwise I use
WRITE(E) to write the new record.

This all works fine for the case of adding a new record, but when I go to
update an existing one the changes don't make it back to the physical
file.  Any ideas?

Thanks,

Kyle Goodwin
Extensicom LLC

> Thank you, that was very helpful.  I'd read all these things
> individually one place or another, but putting them all together in one
> spot it finally clicked.
>
> Kyle Goodwin
> Extensicom LLC
>
> Jonathan Mason wrote:
>
>>Hi Kyle
>>
>>This is more a question about general programming than subfile design
>>and programming, but here goes.
>>
>>A subfile is simply a means of storing and presenting related rows of
>>information on a display.  They are similar to database files in that
>>they store multiple records, but they differ in that the records are
>>stored in the jobs workspace rather than on disk.  They also differ in
>>that they are not keyed, but can be accessed using relative record
>>numbers (RRN) or sequentially.
>>
>>Correct database design has the tables normalised, in other words broken
>>down into their common form.  For example, splitting an invoice into an
>>invoice header file (INVOICES) and invoice lines file (LINEITEMS). This
>>you have done with your tables.
>>
>>The INVOICES file would normally have a key relating to the invoice
>>number (INVOICEID) and the LINEITEMS would have a composite key
>>consisting of the INVOICEID and the invoice line number (INVOICELINE).
>>
>>When you load the records to your subfile you should use the INVOICEID
>>to position the file cursor to the first invoice line for the invoice
>>using the INVOICEID on a SETLL command and then loop through the file
>>using the INVOICEID as the key:
>>
>>* Position to the start of the file...
>>C                   Eval      RRN = *Zeros
>>C     InvoiceID     Setll(e)  LineItems
>>
>> * Read through the file until all invoice lines loaded...
>>C                   Dow       Not %Eof
>>C     InvoiceID     ReadE(e)  LineItems
>>
>> * Populate the subfile record...
>>C                   Eval      SflFld1 = FileFld1
>>C                   Eval      SflFld2 = FileFld2
>>C                   Eval      SflFld3 = FileFld3
>>
>> * Write the details to the subfile...
>>C                   Eval      RRN = RRN + 1
>>C                   Write     Sfl
>>C                   EndDo
>>
>>There are a number of techniques for loading subfiles, the above loads
>>all records at once which you wouldn't normally use where large amounts
>>of data are expected - it's only shown here as an example.
>>
>>The RRN is the position of the record in the subfile, so the first
>>record written is RRN 1, the second RRN 2, etc.  If you know how many
>>records are in the subfile you can read the whole subfile using a loop:
>>
>>C                   For       I = 1 to RRN
>>C     RRN           Chain(e)  LineItems
>>C                   If        %Found
>>C                   ...
>>C                   EndIf
>>C                   EndFor
>>
>>A good guide to subfile programming is "The AS/400 Programmers Handbook"
>>which has a large section on subfile programming.  Alternatively you
>>could check out the FAQ and the archives on this list.
>>
>>All the best
>>
>>Jonathan
>>
>>
>>
>>
>>
>>
>
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