Re: Use of Union

From: Alan <alanshein_at_spambuster.erols.com>
Date: Tue, 27 Mar 2001 11:04:15 -0500
Message-ID: <99qdk8$arq$1@bob.news.rcn.net>

To clarify my previous message, the relational operation "union" eliminates duplicates, so the SQL operation UNION satisfies this. UNION ALL is an SQL construct that maintains the duplicates.

"James Chapman" <JC121123_at_nospam.ncr.com> wrote in message news:3abff3b8_at_rpc1284.daytonoh.ncr.com...
> Yes, that's ANSI. It seems to me that UNION (without ALL) is the true
> union. I don't recall any concept of duplicates in set theory.
>
> "JRStern" <JRStern_at_gte.net> wrote in message
> news:3abfd637.31808748_at_news.gte.net...
> > On Mon, 26 Mar 2001 16:04:53 -0500, "Alan"
> > <alanshein_at_spambuster.erols.com> wrote:
> > >Except that in Oracle SQL there is a UNION and a UNION ALL. UNION ALL
is
the
> > >true union. UNION is more like a "union distinct"
> >
> > Believe that's ANSI.
> >
> > J.
> >
>
>
Received on Tue Mar 27 2001 - 10:04:15 CST