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

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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