Re: finding a suitable key

["Martin Rowe" <martin@xxxxxxxxxxxxxxxxxxxx>]

 Hi Juris

We have the same requirement for a number of files. We start by getting the
next sequential number/value from a data area, then dip into code like yours
to make sure it's unique. When a gap is found, the key is used for the
WRITE, incremented (add one, or A --> B, etc) then the data area is updated
with the new value (as the starting point next time). The only difference is
we just use a SETLL, rather than a CHAIN, and check for the EQ indicator
being *OFF rather than *ON. It's a bit quicker if the loop has to hit a lot
of records before quiting.

If you do find a better solution, please post it here - I could make good
use of it :-)

martin@mjrowe.prestel.co.uk (home)
Martin_Rowe@Moores.co.uk (work)
ICQ UIN# 2020537 - http://www.mirabilis.com


-----Original Message-----
From: Juris Krikis Jr. <juris.rfb@mail.bkc.lv>
To: RPG/400 mailing list <RPG400-L@midrange.com>
Date: 28 August 1997 13:21
Subject: Re: finding a suitable key



>Reading the responses I figured out that I really was not making myself
>clear the first time. I'll try again, if I may. Let's say we have an
>externally described file. The DDS specification looks approximately
>like this:
>A R FIL_REC
>   FIL_KEY 4S TEXT('unique primary key')
>   FIL_DTA      80A TEXT('the data')
> K FIL_KEY
>
>We do have some records already there:
>FIL_KEY FIL_DTA
>------- -------------------------------
> 1      'one'
> 4 'record FOOBAR'
> 0      'null record'
> 99     'some record'
> 2      'BAR'
>
>Now, let's suppose we need to insert a record... We want to find a
>unused primary key for it. What I do now is approximately:
>
>FFil    UF A E       K DISK
>DKey   S            4S 0
>C DoW *In40 = *Off
>C Add 1 Key
>C Key Chain Fil_Rec 40
>C EndDo
>C Move Key Fil_Key
>C Move    Data Fil_Dta
>C Write Fil_Rec
>
>This kinda gets the job done and we happily add a record with key '3'
>(we skipped the '1' and '2' here) there. I don't really like this code,
>because it takes a few lines to write and has to chain through the whole
>file to find the next unused key. It doesn't recognize keys of 0. And it
>changes the buffers (whatever was in Fil_Dta is modified). I was just
>wondering if this could be written easier/better/smarter? Any ideas?
>
> Kind regards, Juris.
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