Re: API to retrieve data field contents

[Rich Duzenbury <rduz-midrange@xxxxxxxxxxxxxxxxxxx>]

On Fri, 2004-11-12 at 11:57, Scott Klement wrote:

> AFIAK, there are two ways to read a database without hardcoding the file
> format into your RPG program:
> 
> a) The ILE C _Ropen(), _Rread(), etc APIs work nicely from RPG. I'm
>     using these in my FTPAPI project as part of the process of FTPing a
>     database file.
> 
> b) SQL allows you to read records with a variable filename/layout as well.
>     I don't have any direct experience with this, but many people have
>     suggested it before (This question seems to come up at least once
>     a month on one mailing list or another.)

And the third way, the original way, RPG.  Create an F spec for an
internally described file with the maximum record length, and user
controlled open.  Call in 'input'.  The override to a 'real' file.  Open
it.  You can now read any record by relative record number.  

If you want keyed access, define the F spec with an index field length,
I think I used 256 in the old days.  Construct a key by concatenating
the fields to match the key, and chain for any record you please.

You will have to manually extract field data from the record, based on
the record layout but that's not too tough.

This is how the old DSPIF and DSPPF utilities worked, and it still works
well today AFAIK.

--
Regards,
Rich

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