Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!lll-lcc!pyramid!voder!blia!billc
From: billc@blia.UUCP
Newsgroups: comp.databases
Subject: Re: Ingres: SQL or QUEL ?
Message-ID: <2009@blia.BLI.COM>
Date: Thu, 2-Apr-87 15:45:04 EST
Article-I.D.: blia.2009
Posted: Thu Apr  2 15:45:04 1987
Date-Received: Sat, 4-Apr-87 19:27:07 EST
References: <327@turing.mcvax.cwi.nl> <1902@blia.BLI.COM> <2263@ncoast.UUCP>
Organization: Britton Lee, Los Gatos, CA
Lines: 29
Summary: QUEL references

In article <2263@ncoast.UUCP>, allbery@ncoast.UUCP (Brandon Allbery) writes:
> Can someone please mail me a description of QUEL, or a book about it from
> which I may glean the means to implement a QUEL-type language on top of
> another database manager?  (Prime contender is UNIFY; not only is their

The only stuff I know of that covers QUEL was originally published as technical
reports by the INGRES project at UCB.  Much of this material has been
republished in 
	"The INGRES Papers: Anatomy of a Relational Database System"
		Michael Stonebraker, editor.  Published by
		Addison-Wesley (Reading, MA 01867), 1986.
This book is probably fairly technical, and doesn't include the QUEL
reference manual or tutorial.  The BSD 4.3 documentation has the reference 
manual.

About "calculus" vs. "algebra":  someone's been reading promotional hype.
Good relational query languages should be non-procedural.  That is,
the user should ask for the desired data without specifying how that data
should be fetched.  QUEL is fairly non-procedural.  The semantics of 
SQL subqueries, as described in the ANSI standard, are VERY procedural.
This makes it inherently dificult to optimize SQL, and subverts the
relational goal of hiding data organization from the user.  Again, a
user should be able to ask for data without any procedural baggage --
let the DBMS figure out the query strategy.
-- 
W.H.Coffin.  billc@blia.BLI.COM
 Or, if you really like source routing, try ucbvax!{mtxinu|ucsfcgl}!blia!billc
 >> the usual disclaimer about my employer and my wretched opinions. <<
 >> the usual witticisms that swell netnews to ridiculous proportions. <<