RE: Selecting a calculated date within a logical file.

I agree that performance issues need to be considered in the join scenario 
because it's another access path that will have to be maintained as records are 
added to the file which is more a problem if the transaction rate is high. The 
volume (# records) issue would actually impact all the solutions because each 
involves, essentially, an access path re-build of some sort, either when the 
date is changed in the Join method or when the access path is rebuilt for 
OPNQRYF or CRTLF.  And, you're quite right, I forgot to mention the limitation 
of not being able to update a joined view.

As for the batch solutions, I tend to prefer SQL over OPNQRYF because I'm 
always suspicious that someday IBM's going to yank away the OPNQRYF command and 
I have a belief (maybe not based in fact!) that SQL performs better than 
OPNQRYF.  Of course, SQL doesn't help if you don't have the SQL development 
product.

==Kevin

-----Original Message-----
From: system21-bounces@xxxxxxxxxxxx
[mailto:system21-bounces@xxxxxxxxxxxx]On Behalf Of Rob Rogerson
Sent: Thursday, July 15, 2004 10:01 AM
To: 'System 21 Users'
Subject: RE: [SYSTEM21] Selecting a calculated date within a logical
file.


After reading Kevin's solution (I didn't see it in the first place) I
would agree this may be the best approach if this file requires to be
accessed during the day.  If it is a batch job (for a report) which only
runs infrequently then OPNQRYF may be a better approach.  I think what
needs to be considered is the overhead associated with building an
OPNQRYF versus a permanent file as Kevin suggests.

Robert A. Rogerson

-----Original Message-----
From: system21-bounces@xxxxxxxxxxxx
[mailto:system21-bounces@xxxxxxxxxxxx] On Behalf Of Lemon, Michael
Sent: Thursday, July 15, 2004 9:40 AM
To: 'System 21 Users'
Subject: RE: [SYSTEM21] Selecting a calculated date within a logical fil
e.

Regardless of which approach, you will find it helpful to have an access
path sorted by date to make the rebuild of the logical file (or SQL
view/cursor) less painful.  Especially if it is a large file (which most
transactional files tend to be).

Of all the approaches that I've heard so far, aesthetically I like the
Join
logical approach the best.  But, you may run into some performance
issues if
this is a high volume file.  Also, you can't update a join logical file.

-Mike


-----Original Message-----
From: Rob Rogerson [mailto:rrogerson@xxxxxxxxxxxxxxxxx] 
Sent: Thursday, July 15, 2004 9:32 AM
To: 'System 21 Users'
Subject: RE: [SYSTEM21] Selecting a calculated date within a logical
file.


I suggested using OPNQRY based on

Jon Wadey - 'What I am trying to achieve is to set-up a logical that
will
only pick-up the previous days transactions.'

Since the previous day is always changing the selection criteria would
be
ever changing as well.  Selection criteria in an OPNQRYF would
accommodate
this.  Another solution would be to use SQL...

Robert A. Rogerson

-----Original Message-----
From: system21-bounces@xxxxxxxxxxxx
[mailto:system21-bounces@xxxxxxxxxxxx]
On Behalf Of Brunk, Kevin
Sent: Thursday, July 15, 2004 9:15 AM
To: System 21 Users
Subject: RE: [SYSTEM21] Selecting a calculated date within a logical
file.

Margaret,

I'm not sure I understand your solution.  There is no "select" parm on
the
CRTLF command.  He'd have to write a program that would generate DDS
source,
that would accept the parm you suggest, and insert it into the source,
then
run the CRTLF command over this generated source.  Rob's solution using
OPNQRYF would work in concert with yours, since OPNQRYF allows the
selection
criteria to be specified in the command.  But, if Jonathan is seeking a
view
that persists beyond the life of the CL program, he couldn't use
OPNQRYF.

==Kevin

-----Original Message-----
From: system21-bounces+kbrunk=wabutler.com@xxxxxxxxxxxx
[mailto:system21-bounces+kbrunk=wabutler.com@xxxxxxxxxxxx]On Behalf Of
mslayton@xxxxxxxxxxx
Sent: Thursday, July 15, 2004 8:49 AM
To: System 21 Users
Subject: Re: [SYSTEM21] Selecting a calculated date within a logical
file.


If you are going to use CL to set up and run this job, there is another 
way.  You can create the logical file in the cl and pass it a parm for
the
select part of the logical file,  and then delete the file when you get 
done with it. 
Thanks,  Margaret 



"Jonathan Wadey" <Jon_Wadey@xxxxxxxxxxxxxxxxxx> 
Sent by: system21-bounces@xxxxxxxxxxxx
07/15/2004 07:08 AM
Please respond to
System 21 Users <system21@xxxxxxxxxxxx>


To
system21@xxxxxxxxxxxx
cc

Subject
[SYSTEM21]   Selecting a calculated date within a logical file.






Dear All,

Is it possible, and if so does anybody know how, to do a file selection
on a
date field within a logical file.

What I am trying to achieve is to set-up a logical that will only
pick-up
the previous days transactions.

TIA

Jon





Jon_Wadey@xxxxxxxxxxxxxxx

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