Re: SELECT within the FROM clause?

From: Robert Klemme <shortcutter_at_googlemail.com>
Date: Sun, 10 Sep 2006 16:52:13 +0200
Message-ID: <4min4vF6c35hU1@individual.net>

HansF wrote:
> On Sat, 09 Sep 2006 22:34:31 +0000, Mladen Gogala wrote:
>

>> On Sat, 09 Sep 2006 21:52:39 +0000, Dereck L. Dietz wrote:
>>
>>> Okay thanks.  Would you happen to know of the top of your head if it is as
>>> efficient as creating an actual view to put in the query or are they about
>>> the same?
>> They're about the same. You can even name your inline view by using
>> subquery factoring (WITH clause).

>
> Further - in those cases where the inline view is reused (occurs several
> times in the query) using the WITH clause can result in amazing
> performance benefits

Learn something new every day: I knew inline views but did not know subquery factoring clauses. This is amazing: "Oracle Database optimizes the query by treating the query name as either an inline view or as a temporary table." (SQL Reference). The documentation seems to indicate that this is the major difference between an inline view and a SQF (apart from the syntax of course)? Did I miss anything?

Kind regards

robert Received on Sun Sep 10 2006 - 09:52:13 CDT