Re: getting the results of a sub select
Re: getting the results of a sub select
- Subject: Re: getting the results of a sub select
- From: Chuck Hill <email@hidden>
- Date: Tue, 15 Mar 2005 18:06:35 -0800
On Mar 15, 2005, at 6:00 PM, Theodore Petrosky wrote:
But it sounds to me that I would be better off
creating a view in the database and just creating a
link to the view. The view would include the
subselect.
CREATE VIEW myview AS
SELECT ji.jobnumber, (SELECT ci.cname FROM
clientinfo ci WHERE (ji.acode = ci.acode)) FROM
jobinfo ji;
now I can avoid totally the whole relationship
thing....
But but but you _don't_ want to _avoid_ the relationship thing. You
_want_ to use them.
I feel that I want to push the backend to do some of
the work. Please correct me if this is the wrong
approach.
It's wrong. :-) Trust in EOF. Don't optimize. It was done for
you, years ago, by excellent developers. There may come a time when
you need to consider optimization. This is not that time.
Chuck
I am more that egar to learn this new (to me
new) method. I am having a few problems with some of
the concepts.
Ted
--- Arturo Perez <email@hidden> wrote:
Ken Anderson wrote:
Ted,
You need to think of jobs and clients as objects
that have
relationships to each other. If you continue to
think about things in
terms of SQL and specialized queries, you're going
to have a hard time
with EOF (the database layer of WebObjects).
This can not be emphasized enough. If you can stop
thinking about the
SQL and just concentrate on what you need to do you
will avoid a lot of
frustration. EOModeler can be very helpful in this
respect. For a
neophyte WO person just let EOF do what it wants.
When it can't do
something or you're tempted to change how EOF has
defined something come
check with this list first. Otherwise you'll be
in for a world of hurt.
One thing that's important to realize here is
that, by default, EOF
will make a trip to the database for each client
you need to fetch. If
you're displaying client.cname in a table or
something, that can become
very inefficient.
Just to clarify this section as it sounds as if EOF
will fetch each
attribute of an object one at a time. EOF will
fetch the entire object
and all its attributes. However, for relationships,
EOF will place a
fault in the object as a stand-in to avoid joins &
the possibility of
loading hundreds of objects when you only need one.
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