Re: oracle query

In article <95eq8n$8o2$1_at_nnrp1.deja.com>,   Vadim Tropashko <vadimtro_at_yahoo.com> wrote:
> In article <95ep49$7ih$1_at_nnrp1.deja.com>,
> Aloha Kakuikanu <alohakaku_at_yahoo.com> wrote:
> > I queried oracle
> >
> > select x from dual where x*x=4
> >
> > but got "invalid column name".
> >
> Well, the correct answer you might find on oracle forum. But if you
> still want to do it that way:
>
> select x from (
> select 1 as x from dummy
> union
> select 2 as x from dummy
> union
> select 3 as x from dummy)
> where x*x=4
>
Your method is opposite to the old technique of quantifier elimination from model theory. See section #10 from:

Constraint Databases: A Tutorial Introduction J. Van den Bussche , SIGMOD Record, Sept 2000

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http://www.deja.com/ Received on Fri Feb 09 2001 - 20:14:50 CET