RE: Query/400 to RPG program

Actually not.  If the changes to the customer master do not need to be
placed in the join logical then don't change the join logical.  If you build
all your logical files, naming all the fields you want in them, then you do
not need to change ANY programs that use the logical files.  The records
formats for the logical, join or not, will not change unless you also add
the field to the logical.

This gives you more flexibility to change your physicals without changing
your entire system.  This is what give a Relation Data Base its power.
Having several views of a physical file does not add lots of overhead to the
data base  manager.  Having several access paths does.  DB2/UDB or what ever
it is call today, share access paths between views.

Now if you do not name the fields in your views and use the record format
name from the physical, well any change to the physical is reflected in your
logical because you share the view in the logical with the physical.


Christopher K. Bipes     mailto:ChrisB@Cross-Check.com
Sr. Programmer/Analyst   mailto:Chris_Bipes@Yahoo.com
CrossCheck, Inc.         http://www.cross-check.com
6119 State Farm Drive    Phone: 707 586-0551 x 1102
Rohnert Park CA  94928 Fax: 707 586-1884

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-----Original Message-----
From: Steve Raisor [mailto:sraisor@earthlink.net]
Sent: Monday, February 28, 2000 9:42 AM
To: RPG400-L@midrange.com
Subject: Re: Query/400 to RPG program


Dave,

        I do understand what you are saying, and I agree some joins are
fine.  We've just found it's easier to say no joins, that way the programmer
doesn't have to decide whether the join they are about to make meets the
criteria that you are describing.  To me, it also makes file changes more
difficult.  For example, if your order file has a join logical with the
customer file, and for the sake of argument a large amount of programs use
that logical because it's key structure is what they needed.  Lets say only
half of the programs using the join logical use fields from the customer
master.  Then, a database change comes along for the customer file.  Now you
must recompile all the programs that are over that join not just the ones
that accessing the customer information.  That's a simple example, what if
the customer file is joined into 20 files on the system.  Suddenly, the
database change to the customer file just got to be much more difficult that
it might have been.

Steve Raisor
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