Re: Logical File or OPNQRYF or anyother way ?

[rob@xxxxxxxxx]

Alternative is imbedded SQL.
http://publib.boulder.ibm.com/infocenter/iseries/v5r3/ic2924/info/rzajp/rzajpkickoff.htm
or look for SQL at
http://store.midrange.com/

Even then, the logical, (or index), may help the performance of the 
OPNQRYF or imbedded SQL.

Pros/cons?
Performance obviously.
Additional indexes on a file may have a performance impact on the update 
of the based file.  However, the impact is not nearly as significant as it 
was in the very early releases of OS/400.
My personal preference is Imbedded SQL over OPNQRYF.  I find it easier to 
understand and maintain, and the newcomers to programming seem to grasp it 
faster.

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





"Malini Rao" <malini2005@xxxxxxxxxxxxxx> 
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03/04/2005 10:40 AM
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Subject
Logical File or OPNQRYF or anyother way ?






Here is a basic question as I am new to AS/400  

I have a physical file which has millions of records, and this physical 
file gets updated quite frequently by various programs in the application. 


I have to develop 2 programs pertaining to an enhancement request.

Program 1 

Needs to read the file selectively based on two fields of the physical 
file , perform calculations on the selected records and update them. There 
is no existing logical file on the physical with these 2 fields as a key
 
Program 2 

Needs to read (only)the file selectively. File is opened in input mode 
only.

Which is the more efficient method in each case - creating a logical file 
with the 2 fields as key or using an openquery with select on the 2 fields 
before each program is called. Any other efficient way ?
 
Also :- What are the scenarios where a logical file is preferred over an 
open query file and vice-versa ?

Thanks in advance
Malini
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