Re: SQL performance question 1

Why select a field? Why do a loop?

Either Select '1' into :indicator from myfile where key = : hostvar fetch
first row only

Or better

SETLL KEY FILE;
Indicator = %Equal(FILE);




Michael Schutte
Admin Professional
Bob Evans NEW! Chicken Fried Chicken Deep-Dish Dinner: Taking Homestyle to
New Heights! Try all three Deep-Dish Dinners, starting at $5.99. For more
information, visit: http://www.BobEvans.com/DeepDishDinners


rpg400-l-bounces@xxxxxxxxxxxx wrote on 12/18/2008 09:16:41 AM:

Hi,

A lot of our developers have recently been introducing SQL into
their RPG code.

We've had a discussion to see how SQL is being implemented.

A lot have replaced this kind of loop:

SETLL key file
dou %eof(file)
READE key file
if %eof
iter
endif

If condition
indicateur = *on
leave
endif
enddo

to see if a row exists, by this :

Select count(*) from myfile where key = : hostvar

I have advised :

Select key from myfile where key = : hostvar fetch first row only.


Is there a better way? Is this a standard way to see if a row
exists? I know there is EXISTS( ) but that would be the same request
(according to visual explain).

Does the RPG version still have any advantages?

Thanks.



--
This is the RPG programming on the IBM i / System i (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.