Re: View for prime numbers

Hello,

"Christian Kienert" <Christian.Kienert_at_gmx.de> wrote in message news:bvddiu$94e$1_at_ngspool-d02.news.aol.com...
> Hi,
>
> We are just discussing "you can do almost everything
> using a view". Of course the view might become a large
> one, but it should be possible to do it with a view.
>
> Any ideas on how to write a view that returns the
> prime numbers within a table of numbers?
>
> e.g.
> create table NUMBERS (number integer);
> create view PRIMES (number) as ???;
>
>

Well, it's trivial if you define a function that checks for primality:

• Naive primality check create or replace function isprime(p_number int) return int as l_isprime int default 1; l_d int default 2; begin while l_d >= 2 and l_d <= sqrt(p_number) loop if mod(p_number, l_d) = 0 then l_isprime := 0; end if; l_d := l_d +1; end loop; if p_number = 1 then return 0; else return l_isprime; end if; end; /

create view primes as select * from numbers where isprime(number)=1;

Rgds.

VC Received on Fri Jan 30 2004 - 14:43:27 CET