Re: does a table always need a PK?

From: Mikito Harakiri <mikharakiri_at_ywho.com>
Date: Wed, 3 Sep 2003 14:18:59 -0700
Message-ID: <t1t5b.23$eu1.263@news.oracle.com>

"Mikito Harakiri" <mikharakiri_at_ywho.com> wrote in message news:4Ls5b.22$eu1.271_at_news.oracle.com...
> MEDIAN is redundant:

select sum(sal)/count(1) from (

   select

      sal,
      (select count(1)+1 from emp ee where ee.sal < e.sal) rn

   from emp e
)
where rn in (

   select min(rn) from (

      select
         (select count(1)+1 from emp ee where ee.sal < e.sal) rn,
         (select count(1) from emp) rowcount
      from emp e

   ) where rn >= (rowcount+1)/2
) or rn in (

   select max(rn) from (

      select
         (select count(1)+1 from emp ee where ee.sal < e.sal) rn,
         (select count(1) from emp) rowcount
      from emp e

   ) where rn <= (rowcount+1)/2
) Received on Wed Sep 03 2003 - 16:18:59 CDT