AW: SQL views

["BirgittaHauser" <Hauser@xxxxxxxxxxxxxxx>]

> > And how does one change a view in order to add a field?

Just do a reverse engineering (to get the current SQL-Statement to create
the view).
Reverse engineering can be done with iSeries Navigator database. Position on
the database object, right click and generate SQL.
Add the new field into the script and recreate the view.
 
> > If an RPG program uses that view (aka LF) does it require recompiling if
the view is changed?
It's the same behaviour as adding a new field into a logical file or a
physical file.
Recreate your RPG-Program

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!"

-----Ursprüngliche Nachricht-----
Von: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von Paul Nelson
Gesendet: Wednesday, August 08, 2007 22:32
An: 'Midrange Systems Technical Discussion'
Betreff: RE: SQL views


And how does one change a view in order to add a field? If an RPG program
uses that view (aka LF) does it require recompiling if the view is changed?

Paul Nelson
Cell 708-670-6978
Office 512-392-2577
nelsonp@xxxxxxxxxxxxx

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of BirgittaHauser
Sent: Wednesday, August 08, 2007 3:18 PM
To: 'Midrange Systems Technical Discussion'
Subject: AW: SQL views

Hi,

Yes, the optimizer will evaluate and may use access path built (SQL indexes
or DDS described logical files) over the physical files specified in the
view. 
But a view must not be updated when the base tables are changed (contrary to
keyed DDS described files or SQL indexes). That's why you can have thousands
of views, without any performance impacts.


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!"



-----Ursprüngliche Nachricht-----
Von: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von Nathan Andelin
Gesendet: Wednesday, August 08, 2007 22:06
An: Midrange Systems Technical Discussion
Betreff: Re: SQL views


> Birgitta H. wrote: Because a view has no access path, access path
> > maintenance is always rebuilt.

Doesn't the query engine use existing access paths of physical files
referenced through views, when available?

Nathan.