RE: SETLL in SQL ?

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-
bounces@xxxxxxxxxxxx] On Behalf Of Joe Pluta
Sent: Saturday, October 13, 2007 9:14 AM
To: 'RPG programming on the AS400 / iSeries'
Subject: RE: SETLL in SQL ?

From: Paul Raulerson

Joe - go read up on scrollable cursors. You are too intent on making

the

point that you cannot do keyed reads.
What I reacted to was plain and simple your statement that you cannot

move

backwards in a cursor without
closing and opening it.

I never said that, Paul. Please quote the post in which I said you
could
not move backward. I just said that if your cursor starts at "G", then
you
can't read the "F" records.

Like I said, go read up on scrollable cursors, they are available on
i5OS/OS400, at least from v5.2 up. You do not have to
close the cursor to position to the previous record, and the start of

the

cursor, and the end, and any record in between,
or relative to your current position.

Paul, I wrote a training course on using JDBC, including cursors. I'm
pretty comfortable with how they work.

Great! I teach Software Engineering as a sideline, but it doesn't mean that
I cannot learn new things.

As for positioning within an SQL cursor by key- well - that seems

more

than a little silly to me.

Well, that's your opinion. We all have one. In my experience, the
ability
to order a large set of data and then move around in that subset
quickly is
relatively important.

Real-world example: I might want to create a list of all memory chips,
sorted first by size then by price. I might want to jump back and
forth
from the cheapest 512MB chips to the cheapest 1GB chips so I can decide
whether to use smaller chips and more slots, or larger chips and less
slots.
If I can position by key (which I can do, by the way, using OPNQRYF), I
can
use a single very fast I/O statement to jump back and forth. With SQL,
I
have to rebuild the cursor each time.

Or you can design the application differently. Or use two queries, or table
up the starting records of
interest, or... any of a lot of different techniques. This is pretty much a
strawman argument, because
it is an argument built only to prove your point... <grin>

Anyway, this part of the thread has devolved from how to do something
(fact)
to whether you think it's silly (opinion), and at that point there are
diminishing returns.

That's mostly because you have a bit of attitude if anyone appears to be
challenging you, even when they are not. Read what I wrote - I really did
just ask you a question. You layered on the attitude mate. ;)

What I asked was if the 400 supported scrollable cursors - which once I
spent the
20 minutes to dig in the docs, it does. Scrollable cursors offer several
possible
solutions to the problem that you appear to have not considered.

Design the query
so your data comes back exactly in the order you need it, and with

all the

data you need available for each record.

Yeah, see, here's the thing. Sometimes those pesky users just refuse
to
conform to my idea of the order I need it, and sometimes they don't
have the
time to wait for me to rebuild a cursor every time they want to look at
something.

If the task doesn't fit into SQL, then use something else, or

redesign the

task.

Well, see, we agree after all. :)

As is usually the case when you get down to the hard facts.

Joe

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