Re: CHGPF and ALTER TABLE

[Vern Hamberg <vhamberg@xxxxxxxxxxx>]

Eric & Jerry

Attempting to find an easier way!!

I suppose you could simply add ALTER TABLE statements as needed to an 
existing script - then you have the history and all - of course, it gets 
ugly to have a CPYF executed under the covers for every ALTER TABLE 
statement. But then you could keep just the most current ALTER TABLE, 
that'd be like DDS, where the source doesn't have cascading changes.

Not we don't do this, so this is all idle speculation, right?

Vern

Jerry Adams wrote:
> Vern and Eric,
>
> Thanks for the replies.  
>
> Well, you can use DDS and CHGPF to re-order the fields in a physical file, though I fail to see why one would want to do that.  I have used it, usually, to add new fields or drop unnecessary filler fields.  
>
> I agree with Eric that it could be a pain to keep track of a table's creation with a set of CREATE TABLE and ALTER TABLE scripts.  Maybe MKS, et al, could keep track of this easily, but I like to keep things simple and as easily understandable as possible for both me and the next guy/gal.
>
> Jerry C. Adams
> IBM System i Programmer/Analyst
> --
> B&W Wholesale
> office: 615-995-7024
> email:  jerry@xxxxxxxxxxxxxxx
>
>
> -----Original Message-----
> From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Vern Hamberg
> Sent: Monday, July 27, 2009 4:53 PM
> To: RPG programming on the IBM i / System i
> Subject: Re: RPG400-L Digest, Vol 8, Issue 563
>
> Jerry
>
> ALTER TABLE is very much like CHGPF - of course, you need DDS to use the 
> latter. Someone in the thread said that you could re-order fields with 
> CHGPF - have never tried that. I don't think you can with ALTER TABLE, 
> only DROP or ADD to the end. But I've wrong once or twice before.
>
> Vern
>
> Jerry Adams wrote:
>   
> > I, too, have gotten the "Data loss may occur" when using CHGPF.  In all cases it came when I was dropping some filler field that a S/34/36 programmer (that did not really understand blocking) had inserted to make the field some factor of 256.  Pressing help (F1) on the error will, IIRC correctly, tell you what field is being dropped or truncated.
> >
> > I have taken to using SQL's DDL to define tables in the last couple of years.  I have never had to change those tables, but I have wondered if ALTER Table worked like CHGPF.  Haven't tried it nor RTFM nor searched the archives in this regard.  When a real need arises, I will.
> >
> > Thanks.
> >
> > Jerry C. Adams
> > IBM System i Programmer/Analyst
> > --
> > B&W Wholesale
> > office: 615-995-7024
> > email:  jerry@xxxxxxxxxxxxxxx
> >
> >
> > -----Original Message-----
> > From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of dale janus
> > Sent: Monday, July 27, 2009 8:16 AM
> > To: rpg400-l@xxxxxxxxxxxx
> > Subject: Re: RPG400-L Digest, Vol 8, Issue 563
> >
> > Hmmm, why not use CHGPF?
> >
> > Because old habits die hard?
> >
> > Because the first time I tried CHGPF I got a warning message that scared 
> > me that I could lose data?
> >
> > Because you're in a hurry?
> >
> > CHGPF sounds like a better way of doing things that  I will try next time.
> > Thanks for the suggestions.
> >
> > ---Dale
> >   
> >     
> > > Why do you use CPY instead of just doing a CHGPF on the file once you added the new fields to the source? You can add the fields anywhere you want and the CHGPF takes care of mapping the data 
> > >
> > > -----Original Message-----
> > > From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of dale janus
> > > Sent: Friday, July 24, 2009 4:41 PM
> > > To: rpg400-l@xxxxxxxxxxxx
> > > Subject: Re: timestamp data type in DDS
> > >
> > > Thanks to all who pointed out my dumb mistake of using *nochk instead of 
> > > *map and *drop.   That fixed it.
> > >
> > > I wish PHP would say "invalid data"  instead of Fetch failed.  But at 
> > > least now I know what to look for.
> > >
> > > I will sign up to midrange -l and ask future questions like this over 
> > > there, for those who suggested that approach.
> > >
> > > Thanks.
> > >
> > > ---Dale
> > >
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