Re: Chain vs SetLL/ReadE

On Tue, 2008-09-02 at 08:34 -0500, Chandra Krieg wrote:

Hello all,

I have been told that the preferred method of random record retrieval is to use the SetLL, then do a ReadE and check for the %EOF indicator.

Why is this preferred over using a Chain with %found or even checking for %Equal on the SetLL before reading the file? I have been told that the Chain doesn't do what I'm expecting it to but I've never had issues in the past.

I have read the archive posts and found opinions on the subject but no concrete explenation as to why. As with some of the posts I don't understand why you would want to readE the file if the SetLL didn't find an %equal match or why if you plan to read the file a chain isn't appropriate.

I'm being told to use the following code instead of a Chain.

SetLL (KeyFields) FIleName;
ReadE (KeyFields FIleName;
DoW Not %EOF(FIleName);
do my stuff
ReadE (KeyFields) FileName;
EndDo;

Well, I can imagine that it might be deemed a bit simpler to avoid
having both a CHAIN and a READE for one file in one chunk of code. But
my own taste would be to have only one READE, even at the cost of two
more lines of code.

SetLL (KeyFields) FileName;
DoW 0=0;
ReadE (KeyFields) FileName;
if %eof( FileName );
leave;
endIf;
do my stuff
EndDo;

Hope I do not sound too much like a broken record.

Cheers,
Terry.

Any explanations would be helpful!

TIA!

Chandra Krieg
i5 Programmer/Analyst
RateWatch
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