Re: check for record changed between read/chain(n) and update

["Gene Burns" <burns.gene@xxxxxxxxx>]

This is interesting.  I tried it with the unlock and without and got the
same result.  The record is unavailable to other applications.  I even
changed the other chain to chain(n) and the record was still not available.


Anyone know why this would be?


On 6/5/07, Wilt, Charles <WiltC@xxxxxxxxxx> wrote:
> You don't need the unlock line assuming the HCLMMAS file's record format
> is CLMMAS in the CHAIN(N)
> before the unlock.
>
> HTH,
> Charles
>
>
>
>
> > -----Original Message-----
> > From: rpg400-l-bounces+wiltc=cintas.com@xxxxxxxxxxxx
> > [mailto:rpg400-l-bounces+wiltc=cintas.com@xxxxxxxxxxxx] On
> > Behalf Of Gene Burns
> > Sent: Tuesday, June 05, 2007 12:17 PM
> > To: RPG programming on the AS400 / iSeries
> > Subject: Re: check for record changed between read/chain(n) and update
> >
> > Thanks, Booth!
> >
> > I setup 2 data structures to start with:
> >
> >      d savmstr       e ds                  extname(hclmmas) prefix(o)
> >
> >      d mstrDS          ds                  likerec(clmmas)
> >
> > then I brought in the data:
> >
> >           chain (cmyrin: cmycin) clmmas;             // get
> > data for pgm
> >           // ekb13  begin block
> >           chain(n) (cmyrin: cmycin) clmmas mstrDS;  // load DS
> >           unlock hclmmas;                             // release lock
> >           savmstr = mstrDS;
> >           // ekb13  end block
> >
> > So now I have the data saved in a data structure, still have
> > the fields available (no rewrite), and no lock on the file.
> >
> > Thanks everyone!
> >
> > On 6/5/07, Booth Martin <booth@xxxxxxxxxxxx> wrote:
> > >
> > > What I do is have three data structures named "Record",
> > "OriginalRecord"
> > > and "NewRecord", all defined like the record format.  Then
> > I prefix two
> > > of the data structures as  "O_" & "N_"   Then, on the
> > original read I
> > > eval OriginalRecord = Record.
> > > Then, later just before I do the locking read I move the
> > Record (which
> > > now has the new values) into NewRecord, If NewRecord =
> > Original then
> > > there are no proposed changes, so bail out.
> > > Otherwise do the locking read and again compare the Record
> > to Original
> > > Record.
> > > If the Original is *not* equal to the Record then there have been
> > > changes at another workstation, do as is appropriate to the
> > business
> > > rules.
> > > If the Original is equal to the Record then its is safe to make the
> > > change, so eval Record = NewRecord and do the update.
> > >
> > > Seems to work fast and is really handy if you also are using
> > > F5=Refresh (Record = OriginalRecord) to let the user undo
> > changes and start over.
> > >
> > >
> > >
> > > Gene Burns wrote:
> > > > I need to change a program to get a record from a file
> > chain(n) and
> > > > let
> > > the
> > > > user work with the data, go to other programs, return to the
> > > > original calling program, etc., then if the user makes changes to
> > > > the data I need
> > > to
> > > > check whether the record has changed before updating.
> > > >
> > > > Is there a better way to do this than bringing the data
> > record into
> > > > a
> > > data
> > > > structure chain(key) file DSname and then rewriting the entire
> > > > program
> > > to
> > > > use the qualified field names from the DS?
> > > >
> > > > I am concerned that even if I do this, that the record could be
> > > > updated
> > > in
> > > > between the chain to get the record into a DS for
> > comparison to the
> > > original
> > > > DS and the actual update.
> > > >
> > > > Gene
> > > >
> > >
> > > --
> > > ---------------------------------
> > > Booth Martin
> > > http://www.Martinvt.com
> > > ---------------------------------
> > >
> > > --
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