Path: utzoo!attcan!uunet!cucstud!lcain
From: lcain@cucstud.UUCP (Leroy Cain)
Newsgroups: comp.databases
Subject: Re: Sybase bug?
Summary: Or does = Union
Message-ID: <2099@cucstud.UUCP>
Date: 9 Jul 89 17:55:18 GMT
References: <637@cullsj.UUCP> <4982@sybase.sybase.com>
Organization: Columbia Union College; Takoma Park, MD 20912
Lines: 33

In article <4982@sybase.sybase.com>, jeffl@sybase.Sybase.COM (Jeff Lichtman) writes:
> >> > select * from hello where a = 1 or a in (select b from world)
> > 
> > Thus, the predicate a = 1 should be applied to each row of the table
> > hello, and would be true for the one row that exists in table hello...
> > Thus, the result should contain 1 row.
> >
> > Yogesh Gupta.

This is correct!


[ stuff about query plan deleted]

> A previous posting had it right: 'or' does not mean 'union'.

Well in that case a number of text books need rewriting.  A quote from
"An Introduction to Database Systems" by C.J. Date page 264:

"2. R WHERE c1 OR c2
    is defined to be equivalent to
       ( R WHERE c1 ) UNION ( R WHERE c2 )"

> ---
> Jeff Lichtman at Sybase
> {mtxinu,pacbell}!sybase!jeffl  -or- jeffl@sybase.com
> "Saints should always be judged guilty until they are proved innocent..."


MS-DOS Just say NO!!!!!			      OS/2 Why????
Leroy Cain;      Columbia Union College;      Mathematical Sciences Department
7600 Flower Ave. WH406;  	              Takoma Park, Md 20912
(301) 891-4172				      uunet!cucstud!lcain