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

[Booth Martin <booth@xxxxxxxxxxxx>]

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
>