RE: Subfile Processing

Sorry, I wasn't clear:  I'm not looping through all the records, I'm
looping until READC yields an %EOF response.

Kyle Goodwin
Extensicom LLC

> First, don't loop through the whole file.  If the users are modifying
> the records, then READC will be the fastest way to get the modified
> record.  And don't forget that if there is an error, use the return
> record on next read flag.  Saves a lot of headaches.
>
> Marvin
>
>
> -----Original Message-----
> From: rpg400-l-bounces@xxxxxxxxxxxx
> [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of
> goodwink@xxxxxxxxxxxxxx
> Sent: Tuesday, August 09, 2005 12:59 PM
> To: RPG programming on the AS400 / iSeries
> Subject: 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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