Re: Constraining a logical file

Dave Parnin wrote:

I am working on a program that needs to update certain records of a
somewhat large file. Because it could potentially be run multiple times

a

day I would like to limit the number of records that it processes by
creating a logical file (preferably with SQL rather than DDS). There

are

two fields that need to be looked at. FIELD1 could have numerous

possible

values but I'm only interested in A, B, and C. FIELD2 is a status

field.

If it's blank then the record needs to be processed. If it has a value
that I assign, such as X, then it has been previously processed and can

be

skipped in subsequent runs. Basically I want a logical file that does
something like:

If FIELD2 <> 'X'
If FIELD1 = 'A' or FIELD1 = 'B' or FIELD1 = 'C'
process the record
FIELD1 = 'X'
update the record
ENDIF
ENDIF

I've tried setting up a logical using select and omit but it either
includes or excludes too much. I could probably do it with an open

query

file but that introduces a bit of overhead each time the program is run.

Can anybody recommend a good way to do this with SQL? Thanks.

Could you use embedded SQL, select the records into your cursor using
"WHERE field2 <> 'X' AND field1 IN ('A','B','C')"? That should get you
the exact subset of the records in which you are interested.
Alternatively, what about an logical/index that is sorted first by field2,
then field1, and do something like this (off the top of my head - not
tested!)

SETLL ('X':'A') logicalFile;
READ file;
DOW (field2 = 'X' AND (field1 = 'A' OR field1 = 'B' OR field1 = 'C') AND
NOT %eof(logicalFile));
// process file
READ file;
ENDDO

HTH,
Adam

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