RE: File field names

For the arguing that I did (whot most people who know me will tell you that
I do all the time anyhow), you're welcome!

I wrote a reply to this then noticed that it looked pompous so I killed it
and started over.  If I can't have qualified names, I will use prefixes.  I
have had too much trouble when RPG unifies the storage for fields with the
same names.

As far as the problem with moves and copies, I wrote a tiny preprocessor
that simulates a COBOL "move corresponding".  It generates the appropriate
moves and z-adds between structures.

Richard Jackson
mailto:richardjackson@richardjackson.net
http://www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-|-----Original Message-----
-|From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
-|Behalf Of rob@dekko.com
-|Sent: Thursday, October 26, 2000 11:28 AM
-|To: RPG400-L@midrange.com
-|Subject: RE: File field names
-|
-|
-|
-|I understand what you are saying.  Let me restate it.  I have an employee
-|table.  In it I have an employee number and a managers employee number.
-|They should have similar attributes save TEXT and COLHDG.  I'll
-|accept that
-|it would have two field names and a reference would be
-|acceptable.  In this
-|case the employee number would have the same name as the employee
-|number in
-|the rest of the files.  While manager might be called MANAGER with a
-|reference to the other employee number.  A similar example would be the
-|bill of material file containing parent and child.
-|
-|And thank you for the PREFIX.  The canned software did the prefixing
-|manually, in the I specs, prior to RPGIV.
-|
-|
-|Rob Berendt
-|
-|==================
-|Remember the Cole!
-|
-|
-|
-|
-|                    "Richard Jackson"
-|
-|                    <richardjackson@richardja        To:
-|<RPG400-L@midrange.com>
-|                    ckson.net>                       cc:
-|
-|                    Sent by:                         Subject:
-|RE: File field names
-|                    owner-rpg400-l@midrange.c
-|
-|                    om
-|
-|
-|
-|
-|
-|                    10/26/00 11:18 AM
-|
-|                    Please respond to
-|
-|                    RPG400-L
-|
-|
-|
-|
-|
-|
-|
-|
-|
-|I strongly disagree.  Hierarchical metadata with cascaded inheritance of
-|characteristics is very powerful.  Your suggestion makes this critical
-|concept non-workable.
-|
-|For example, suppose that you have a name and address file.
-|Primary key is
-|person_number.  Persons work for companies so you want to associate a
-|person
-|with the company that they work for.  In other words I need a second field
-|in each record for the parent person number.  But person_number and
-|parent_person_number describe almost exactly the same thing and
-|parent_person_number can and should inherit virtually all of its
-|characteristics from person_number.  If I create a new data element called
-|parent_person_number, I break the relationship between person_number and
-|parent_person_number.  If I make a change to the database to make the
-|person_number data element longer, I will not know that
-|parent_person_number
-|is the same thing but that it has a different name because we don't allow
-|inheritance.
-|
-|The first obvious solution is to create a reference from the
-|parent_person_number data element to the person_number data element.  But
-|we
-|end up with exactly the same problem except that it is now in the metadata
-|files - the data dictionary itself.  What to you call the data element
-|where
-|we put the link between the two data elements?  It cannot be called
-|data_element_identifier because each data element row already has a
-|data_element_identifier column.  If I give it a new name, how can I relate
-|the new name to the characteristics.
-|
-|The second obvious solution is to normalize the relationships
-|into a second
-|relationships table containing 5 columns: <parent_type, parent_identifier,
-|child_type, child_identifier, relationship>.  The tricky thing
-|here is that
-|parent_identifier and child_identifier inherit characteristics from all
-|tables and columns with relationships.  When I built this the
-|first time, I
-|made certain that all tables in the database used the same format
-|for their
-|unique identifier.  This imposed some structure on the database
-|that didn't
-|meet all the rules laid down by Codd and Date but it made the design work.
-|
-|Because RPG doesn't support qualified field names, the field name
-|prefix is
-|necessary.  For what its worth, I take a little credit for having that
-|feature in the language.  I was representing my employer at the IBM
-|meetings
-|when RPG 4 was speced.  We stored a prefix in the table definition files
-|for
-|our tables.  Since the factor 1, factor 2, and the result fields weren't
-|big
-|enough for qualified field names and there was no support for qualified
-|field names and it was clear that calc specs weren't going to be
-|completely
-|free format, I argued strongly for the prefix attribute so that the
-|name-space crunch would be reduced.  Some database purists
-|opposed the idea
-|but without qualified field names, their position was too vulnerable.
-|
-|
-|
-|Richard Jackson
-|mailto:richardjackson@richardjackson.net
-|http://www.richardjacksonltd.com
-|Voice: 1 (303) 808-8058
-|Fax:   1 (303) 663-4325
-|
-|-|-----Original Message-----
-|-|From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
-|-|Behalf Of rob@dekko.com
-|-|Sent: Thursday, October 26, 2000 7:59 AM
-|-|To: RPG400-L@midrange.com
-|-|Subject: RE: File field names
-|-|
-|-|
-|-|
-|-|That's your problem, right there.  You're adding a prefix when
-|you code a
-|-|PF.  For example, if you called the item number ITEMNUM in both ITEMMAST
-|-|and ORDDET then a simple query against the file QSYS/QADBIFLD would show
-|-|you everywhere the field is used.  If you want to use the two files in
-|the
-|-|same program then you simply do a PREFIX on the F spec in RPGIV.
-|-|There are
-|-|commercial canned software applications out there which do this.  They
-|-|actually work and make sense.  People can adapt.
-|-|
-|-|Adopting this technique makes referencing obsolete.  Except maybe
-|-|in screen
-|-|or printer files.
-|-|
-|-|Rob Berendt
-|-|
-|-|==================
-|-|Remember the Cole!
-|-|
-|-|
-|-|
-|-|
-|-|                    Marco Facchinetti
-|-|
-|-|                    <facchinetti@yaho        To:
-|-|RPG400-L@midrange.com
-|-|                    o.com>                   cc:
-|-|
-|-|                    Sent by:                 Subject:     RE:
-|-|File field names
-|-|                    owner-rpg400-l@mi
-|-|
-|-|                    drange.com
-|-|
-|-|
-|-|
-|-|
-|-|
-|-|                    10/25/00 06:42 PM
-|-|
-|-|                    Please respond to
-|-|
-|-|                    RPG400-L
-|-|
-|-|
-|-|
-|-|
-|-|
-|-|
-|-|
-|-|
-|-|
-|-|First of all because I think reference is a basic component
-|-|in relational database and it's amazing IBM provides a
-|-|system (R in DDS) and grant you all the informations about
-|-|a filed except the reference field. Check out the api
-|-|format (see the original message) and tell me what else is
-|-|missing.
-|-|
-|-|But basicly because I always (at least I try) to define a
-|-|field only once and attach comments and help on this field.
-|-|I put this field in a file and I use it as a dictionary.
-|-|When I code PF I add a prefix of two char to unique
-|-|identify the field in/from the PF. This is a basic rule
-|-|just to help programmers and doesn't apply to all fields.
-|-|To insert help in display files and to print a documented
-|-|"DSPFFD" I need the referenced fields. Otherwise I have to
-|-|duplicate help pannels and txt members (comments to
-|-|fields).
-|-|
-|-|--- Steve Brazzell <steve@brazzell.com> wrote:
-|-|> That's true, but I didn't think it was part of the
-|-|> original question.
-|-|>
-|-|> Except for building some sort of metadata reference
-|-|> information or
-|-|> attempting to glean field purposes (risky, this way,
-|-|> btw), why would one
-|-|> want to know the referenced field names?
-|-|>
-|-|> This is just a question, not a put-down in any way; I'm
-|-|> just curious.
-|-|>
-|-|> Steve
-|-|>
-|-|>
-|-|> -----Original Message-----
-|-|> From: owner-rpg400-l@midrange.com
-|-|> [mailto:owner-rpg400-l@midrange.com]On
-|-|> Behalf Of Marco Facchinetti
-|-|> Sent: Wednesday, October 25, 2000 7:31 AM
-|-|> To: RPG400-L@midrange.com
-|-|> Subject: RE: File field names
-|-|>
-|-|>
-|-|> But something is missing, at least in V4R4, the
-|-|> referenced
-|-|> field.
-|-|> --- Steve Brazzell <steve@brazzell.com> wrote:
-|-|> > Lance,
-|-|> >
-|-|> > The purest RPG solution I know of is to use the QUSLRCD
-|-|> > API and then read
-|-|> > the results from a user space.
-|-|> >
-|-|> > If you don't care to go this route, though, you can
-|-|> > always do a DSPFFD to an
-|-|> > outfile and then read the records in the outfile.
-|-|> >
-|-|> > Steve Brazzell
-|-|> >
-|-|> >
-|-|> > -----Original Message-----
-|-|> > From: owner-rpg400-l@midrange.com
-|-|> > [mailto:owner-rpg400-l@midrange.com]On
-|-|> > Behalf Of Gwecnal@aol.com
-|-|> > Sent: Tuesday, October 24, 2000 3:27 PM
-|-|> > To: rpg400-l@midrange.com
-|-|> > Subject: File field names
-|-|> >
-|-|> >
-|-|> > I seem to remember someone, sometime posting some REXX
-|-|> > code that would
-|-|> > extract the field names from an externally described
-|-|> > file. I did not save
-|-|> > the
-|-|> > message and now I need to be able to get the field
-|-|> names
-|-|> > out of a file.  Did
-|-|> > anyone keep it or does anyone know how?  TIA, Lance
-|-|> > +---
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