RE: Simple Display file problem

You've never had to use cursors.

Since the beginning you've been able to do SELECT INTO.

The SELECT INTO is used when you only need to return a single row of 1
or more columns.

HTH,

Charles Wilt
--
iSeries Systems Administrator / Developer
Mitsubishi Electric Automotive America
ph: 513-573-4343
fax: 513-398-1121
  

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx 
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Jake M
Sent: Wednesday, September 20, 2006 2:22 PM
To: RPG programming on the AS400 / iSeries
Subject: Re: Simple Display file problem

That looks great. So, no declaring, opening and closing 
cursors? That is
pretty neat.

cheers,

Jake.

On 9/20/06, rob@xxxxxxxxx <rob@xxxxxxxxx> wrote:

Great points.

One "point of information" though.  It's not
/Exec Sql Select ItemNumber, ItemDescription From ItemFile Where
ItemNumber = :Item;
It's
Exec Sql Select ItemNumber, ItemDescription From ItemFile Where
ItemNumber = :Item;

No slash.

Actually it's
Exec Sql Select ItemDescription into :ItemDescription From 

ItemFile Where

ItemNumber = :Item;
After all, if you already know the item number, why move those bytes
around again?  And, on a cursorless select you need the 

into.  But that's

just details.  Your points are well taken.

Rob Berendt
--
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





"Alan Campin" <Alan.Campin@xxxxxxxxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
09/20/2006 01:49 PM
Please respond to
RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>


To
<rpg400-l@xxxxxxxxxxxx>
cc

Subject
Re: Simple Display file problem






<snip>
Thanks for that insight. Can SQL be used in free-form in 

V5R4 without

the
use of /EXEC and and /END-EXEC tags in C specs? Or do we 

still have to

use
/EXEC and /END-EXEC but can get rid of the C specs. We are 

still on V5R3

and
will take some time to get there but such things are really good to
know.
</snip>

New syntax is

/Exec Sql Select ItemNumber, ItemDescription From ItemFile Where
ItemNumber = :Item;

No /End-Exec. Just a semi-colon.

Asked my boss to get V5R4 on order.

<snip>
Yes IBM did give us an easy way create an LF & include only 

the fields

you need...
</snip>

Except the catch. It works and increases performance a lot 

but if I need

to bring in five tables into a program, I am going to have 

to define 5

different logical views unless I can do some joins. Even 

having a tool

to do this, a lot of work and difficult to maintain. I have 

built system

using the techniques but a ton of work.

<snip>
all true Alan. But does a 600 CPW i5 have the horsepower to run pure
SQL instead of RPG?  My guess is it does not.  Fetching thru an SQL
cursor must be slower than setll and reade. The mapping of 

more than a

few SELECT columns would quickly become more cpu intensive 

than a byte

copy into a record format.
</snip>

Actually the opposite is true.

1. New SQL I/O system is 5 to 7 times faster than DDS file.

2. New SQL Index system is 2 to 3 times faster than DDS indexes.

3. SQL has a new query optimizer that is a lot more efficient.

4. Reading in only the data you need is always going to be 

faster than

reading the entire record. A lot of reasons for this 

primarily having to

do with buffers. IBM optimizes the moves but byte moves are just not
going to be significant. Record I/O is the most expensive 

thing in the

system.

5. The other thing with SQL is that you can read multiple 

records into

an array mapped to a user space. You cannot do that with 

Record I/O. If

you are reading multiple tables with selects and reading in multiple
records into a user space, the performance is going to be 

way faster.

All the work is going to happen at the machine level. I 

gave an example

in a previous post.

In short, what used to be true is just not true anymore and 

it is only

going to get better. SQL is present and the future.

The only reason I see to continue a lot of record I/O is severely
unnormalized databases.

--
This is the RPG programming on the AS400 / iSeries 

(RPG400-L) mailing list

To post a message email: RPG400-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/rpg400-l
or email: RPG400-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/rpg400-l.


--
This is the RPG programming on the AS400 / iSeries 

(RPG400-L) mailing list

To post a message email: RPG400-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/rpg400-l
or email: RPG400-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/rpg400-l.

-- 
This is the RPG programming on the AS400 / iSeries (RPG400-L) 
mailing list
To post a message email: RPG400-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/rpg400-l
or email: RPG400-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/rpg400-l.