RE: to_number question
- From: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Thu, 15 Jul 2004 09:36:43 -0700
Of course it works. It is the proper way (without hints) of requesting (and
ensuring) that Oracle to evaluate the subqueries on their own and not merging
them with the rest of the query. Just as "order by" is the proper way of
requesting (and ensuring) the resultrows to be returned in a particular order.
The basic tenet of relational databases, what I have tried to explain in this
last series of posts, is that you must not assume any particular order of
execution of your query, or components of your query.
Any restructuring of the sql syntax is merely superficial, the fact that it
sometimes works in causing the optimizer to change the access plan
notwithstanding. It may quit working with the next upgrade to the optimizer.
Quoting Stephen.Lee@xxxxxxxx:
> > -----Original Message-----
> > One of the ways to make sure that a subquery is evaluated on
> > its own and not
> > flattened (unnested) into the whole query is to use the
> > rownum pseudocolumn:
>
> I got around to trying this, and it works too.
> What a fine list group this is.
>
--
regards
Wolfgang Breitling
Oracle 7,8,8i,9i OCP DBA
Centrex Consulting Corporation
www.centrexcc.com
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