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| DECLARE inside a loop |
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| francoisvdm |
 Posted: Mon Sep 20, 2010 1:05 am Post subject: DECLARE inside a loop |
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Partisan
Joined: 09 Aug 2001
Posts: 332
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What is the effect on memory and CPU if you do a DECLARE inside a loop, ie
| Code: |
WHILE X < Y DO
DECLARE myCount INTEGER 0;
WHILE Z < Q DO
...
END WHILE;
END WHILE; |
versus
| Code: |
DECLARE myCount INTEGER;
WHILE X < Y DO
SET myCount = 0;
WHILE Z < Q DO
...
END WHILE;
END WHILE; |
Thanks
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Francois van der Merwe |
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| mvarghese |
| Posted: Mon Sep 20, 2010 1:49 am Post subject: |
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Centurion
Joined: 27 Sep 2006
Posts: 141
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if possible use WHILE then IF-ELSEIF-ELSE statement .
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Jain Varghese |
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| mqjeff |
| Posted: Mon Sep 20, 2010 1:57 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| I can't say I've specifically tested this, but I'd expect that the differences would be the logical ones. Doing the declare inside the loop will declare more than one locally scoped variable. Doing the declare outside the loop will declare only one locally scoped variable. |
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| Vitor |
| Posted: Mon Sep 20, 2010 4:36 am Post subject: Re: DECLARE inside a loop |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| francoisvdm wrote: |
| What is the effect on memory and CPU if you do a DECLARE inside a loop, |
You'll get Y-1 copies of myCount, with only the most recent one in scope & usable. Local experience with this construction indicates that the unused variables pile up until the loop exits and are then released back into memory. I'd imagine it also takes more cycles to allocate a new variable than set a new one to zero but can't see the extra overhead being significant unless Y is a large number.
I've not seen any docuemntation on this, would be interested in a link to such documentation and personally consider DECLARE inside a loop contact admin programming. Regretably one of the previous coders at this site was fond of this construction & I'm working to eliminate it. 
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