Re: Idempotence and "Replication Insensitivity" are equivalent ?

pamelafluente_at_libero.it wrote:
> The median, like the mean IS an aggregate function.
>
> All dbms implements it.

Look up any math book. Do you see an aggregate symbol except:

i. sigma capital (aka summation)
ii. pi capital (aka product)
iii. /\ (aka min, aka conjunction, aka "for any" quantifier) iv. \/ (aka max, disjunction, "forall" )

? I don't.

Expressing an arbitraty aggregation in terms of these is trivial. You just consult any math dictionary for the formula that defines it in terms of the above four fundamental aggregates and write a corresponding expression in SQL. Received on Sat Sep 23 2006 - 02:43:51 CEST