RE: Record Lock

 <snip>
You could, I suppose, ask for the check date first, and not show the 
check number.
</snip>

That's the way I would approach this then when the user presses Enter to
accept return the check number to the display...

Just my 2 coppers


Thanks,
Tommy Holden


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Booth Martin
Sent: Thursday, June 22, 2006 2:24 PM
To: RPG programming on the AS400 / iSeries
Subject: Re: Record Lock

You could, I suppose, ask for the check date first, and not show the 
check number.

Or, you could get the check number, using an (n) extender on the chain 
opcode, then if everything is  a go, chain again and do the real update.

But, the whole secret, in my opinion, is to find a way to avoid the file

being locked while waiting for user input.



steema@xxxxxxxxxxxxx wrote:

There is a pause for the user to enter the check date. That could be a
problem. I like your idea of immediate update, and then subtract one

in

case the user cancels out.

WHy is the DATA AREA considered, "safer" than a file in this scenario?

Thanks for all your help,
Steve

I believe your problem may originate with the order in which you are
doing things?  Get the existing number, add 1 to it, and immediately
update the file with the new number, thereby unlocking the record.

Then

display it.

If the problem is that the user may cancel out, you can always chain

to

the file, get the new existing number (make sure it is the same as

the

one on the canceled screen), sub 1, and update the file.

As a policy I never leave a file open for a screen program.  Too many
users go to lunch or get a phone call and someone always gets burned,

in

a non-predictable way.



steema@xxxxxxxxxxxxx wrote:

There is one program that generates the check number. It is a simple

RPG

that chains the file by company only, adds 1 to the existing number

and

places this on the screen for the user.

I have put in a chain right there to ensure that this new number

does

not
already exist, and I have also added a log file to this program.

There is also another program that does checks which I am checking

now

but
I beleive it only calls the first program.

I was told that for checks, they don't indicate the division ever,

only

company.

I still want to know what happens to the file lock, when a term.
freezes.

Thank you,

Steve

Now I have found out, that someone here thinks it occurs when the
users
terminal gets LOCKED. But first of all, wouldn't a record lock

remain

in
effect or would the CL program that holds the lock in effect
deallocate
this lock? yet the check number started to change, did change? its

a

bit
confusing, but it makes some possible sense.

Record locks have nothing at all to do with the creation of the

check

number.  Furthermore, _object_ locks (ALCOBJ) have nothing to do

with

the contents of any particular record.  It's hard to tell what you

mean

by 'terminal gets locked.'  Sounds like a program failure of some

sort.

 > I am looking at a situation that occassionaly
 > occurs, that a check number is allowed to be
 > entered that is a dup.

 > the key is CO, Div, batch#, check#,
 > so you could have the same number and a diff batch.

If the key is Co, Div, Batch, Check, then the database designer is
explicitly allowing for duplicate check numbers, as long as they

occur

in a different company or division or batch.

 > Or to put it another way, how would you
 > design such a program in such a
 > way that a dup could NEVER happen?

My choice would be to create a new logical file keyed by check

number,

unique.  That way the database enforces your business rule (no
duplicate
check numbers.)  However, as Lim warns, this could ripple through

the

application, causing problems you don't want if there are already
'duplicate' check numbers in the file.

As Jerry asked, where do these check numbers come from?  Does the
application generate them, or are they input from somewhere (like a
customer payment batch?)  If your application generates the check
number, there are two tried and true mechanisms for guaranteeing a
unique number.  Data area and control file.

*lock in dtaara    // locks dtaara; nobody else can read
add 1 check
out dtaara

'check' chain ctlfile   // locks record; nobody else can chain
add 1 check
update ctlfile

   --buck
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---------------------------------
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http://www.Martinvt.com
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