Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!nrl-cmf!ukma!psuvm.bitnet!uh2
From: UH2@PSUVM.BITNET (Lee Sailer)
Newsgroups: comp.databases
Subject: Re: SQL question
Message-ID: <34586UH2@PSUVM>
Date: 25 Feb 88 14:01:13 GMT
References: <34358UH2@PSUVM> <43005@sun.uucp>
Organization: Penn Sate Erie--School of Business
Lines: 24

In article <43005@sun.uucp>, rfm%urth@Sun.COM (Richard McAllister) says:
>
>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

That is certainly straightforward enough, but still I was surprised.
One of the characterisitcs of SQL, I thought, was that there are ONLY
4 operators, SELECT, INSERT, DELETE, and UPDATE.  I figured that
there would be some tricky way to use a SELECT to do a Union, Intersect,
Difference, etc.

So, how come it is said that SQL has only 4 operators, when obviously
there are more?

               lee