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From: billc@blia.BLI.COM (Bill Coffin)
Newsgroups: comp.databases
Subject: Re: Outer join in SQL
Message-ID: <3668@blia.BLI.COM>
Date: Tue, 24-Nov-87 15:04:24 EST
Article-I.D.: blia.3668
Posted: Tue Nov 24 15:04:24 1987
Date-Received: Sat, 28-Nov-87 05:43:32 EST
References: <1804@cognos.UUCP>
Organization: Britton Lee, Inc. @ Berkeley, CA
Lines: 25
Summary: Britton Lee has it.

In article <1804@cognos.UUCP>, garyp@cognos.uucp (Gary Puckering) writes:
> One thing that is noticeably missing from most relational dbms 
> implementations is the Outer Join operation. 
> [ ... ]
> a)  Which relational dbms products currently provide an outer join
>     capability (and with what syntax)?

Britton Lee SQL and IDL provide outer joins, with the following syntax:

   SELECT a.emp-no, fname, lname, AVG(rating), salary
   FROM employee a, project-rate b
   WHERE a.emp-no *= b.emp-no

note the "*=".  BLI also supports "=*", "*>", "*<>", and so on.  That is,
every relational predicate can be restated as an outer join.  (This leads 
to some semantic gotchas in more complex queries, but is also more
flexible than the PRESERVE syntax.)
 
> c)  Will the performance of a "real" outer join be significantly
>     better than that of a "simulated" outer join?  

Yes.
-- 
W.H.Coffin.  billc@blia.BLI.COM (ucbvax!{mtxinu|ucsfcgl}!blia!billc)
 >> the usual disclaimer about my employer and my wretched opinions. <<
 >> the usual witticisms that swell netnews to ridiculous proportions. <<