Re: does a table always need a PK?
Date: Tue, 2 Sep 2003 18:21:12 -0700
Message-ID: <wub5b.21$1o4.1267_at_news.oracle.com>
"Lee Fesperman" <firstsql_at_ix.netcom.com> wrote in message
news:3F553DDD.50EB_at_ix.netcom.com...
> + SUM() is just one type of aggregate function. The other common ones
don't have a
> corresponding simple operator. The rules should be the same for all
aggregate
> functions.
MAX have a corresponding 2 argument operator,
MIN the same,
AVG = SUM(val)/SUM(1) is redundant
COUNT is redundant
...
Thesis. Agregate functioner is either redundant or has a corresponding 2 argument operator.
MULTIPLY is an interesting case. On one hand, it has a corresponding binary operator *, while on the other, it can be reduced to exponentiation, logariphm and summation.
I see some fancy aggregate operators on the list (like STDDEV), so that maybe somebody would be so kind to confirm/refute the thesis for those beasts. Received on Wed Sep 03 2003 - 03:21:12 CEST