Re: Implicitly hidden column & EXTNAME D/S

Agreed, we usually don't need all of them.

Maybe somebody can create a RFE requesting the pre-compiler to auto
generate, from the Select statement, the Ds definition (qualified of
course) with null attributes usable via %nullind. ;-)

HTH
--
Marco Facchinetti

Mr S.r.l.

Tel. 035 962885
Cel. 393 9620498

Skype: facchinettimarco


Il giorno ven 1 mag 2020 alle ore 20:17 Birgitta Hauser <
Hauser@xxxxxxxxxxxxxxx> ha scritto:

Do you really need all columns in your programs or only a sub-set?
I assume in 99% of all cases you only need a sub-set.
If you list your columns, you do not have to recompile if your table is
changed, i.e. you only have to recompile or change where you use the
new/changed field.
With a list of data the query optimizer might be able to perform a IOA
(Index Only Access), i.e. finds an index where all information you request
can be found within the key values. In this way there is no need to access
the table data themselves..

Mit freundlichen Grüßen / Best regards

Birgitta Hauser


"Shoot for the moon, even if you miss, you'll land among the stars." (Les
Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
"What is worse than training your staff and losing them? Not training them
and keeping them!"
„Train people well enough so they can leave, treat them well enough so they
don't want to.“ (Richard Branson)


-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Justin
Taylor
Sent: Freitag, 1. Mai 2020 19:19
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: RE: Implicitly hidden column & EXTNAME D/S

" BTW it is never a good ide to use SELECT *!"

Personally, I'd say "almost never". Can you explain why it's better for
the
SELECT (in static SQL) to explicitly list every single column rather than
doing SELECT *?


Thanks



-----Original Message-----
From: Birgitta Hauser [mailto:Hauser@xxxxxxxxxxxxxxx]
Sent: Friday, May 01, 2020 10:38 AM
To: 'RPG programming on IBM i' <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: RE: Implicitly hidden column & EXTNAME D/S

That is a problem with RPG / SQL and embedded SQL!

Even though the implicitly hidden columns are not displayed when executing
SELECT * FROM, the RPG external data structure based on the table includes
all columns (also the implicitly hidden ones).
You may create an additional view, based on SELECT * (without the
implicitly
hidden columns) and then use this view as base for the external data
structure.

BTW it is never a good ide to use SELECT *!
It is much better to retrieve only the information/columns you really need.

Mit freundlichen Grüßen / Best regards

Birgitta Hauser


"Shoot for the moon, even if you miss, you'll land among the stars." (Les
Brown)
"If you think education is expensive, try ignorance." (Derek Bok) "What is
worse than training your staff and losing them? Not training them and
keeping them!"
"Train people well enough so they can leave, treat them well enough so they
don't want to." (Richard Branson)

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