Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!oliveb!sun!urth!rfm
From: rfm%urth@Sun.COM (Richard McAllister)
Newsgroups: comp.databases
Subject: Re: SQL question
Message-ID: <43005@sun.uucp>
Date: 24 Feb 88 16:51:14 GMT
References: <34358UH2@PSUVM>
Sender: news@sun.uucp
Reply-To: rfm@sun.UUCP (Richard McAllister)
Organization: Sun Microsystems, Mountain View
Lines: 17
Keywords: SQL UNION
Summary: SELECT ... UNION SELECT ...

In article <34358UH2@PSUVM> UH2@PSUVM.BITNET (Lee Sailer) writes: 

>This morning I am wondering, how do you do a simple relational UNION in SQL?
>That is, given two relations, R1 and R2, how do you create R3 that contains
>those tuples that are in either R1, R2, or both, assuming that R1 and R2
>have the same attributes?

You write 

   SELECT * FROM R1
   UNION
   SELECT * FROM R2

to get the rows of R3.  If you want to create a new "virtual" relation R3
(SQL calls this a VIEW) you're pretty much out of luck as few
implementations of SQL allow basing a VIEW on a UNION.

Rich