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From: billc@blia.UUCP
Newsgroups: comp.databases
Subject: Re: Ingres: SQL or QUEL ?
Message-ID: <1902@blia.BLI.COM>
Date: Thu, 26-Mar-87 14:43:30 EST
Article-I.D.: blia.1902
Posted: Thu Mar 26 14:43:30 1987
Date-Received: Sat, 28-Mar-87 06:38:14 EST
References: <327@turing.mcvax.cwi.nl>
Organization: Britton Lee, Los Gatos, CA
Lines: 39
Summary: SQL vs. QUEL

In article <327@turing.mcvax.cwi.nl>, johan@mcvax.cwi.nl (Johan Wolleswinkel) writes:
> 
> 1. The `holy' :-) Date wrote, that QUEL was `better' than SQL.
>    Comparison of the manuals didn't show any difference
>    in functionality (of course with the exception of the macro
>    facility in the interface to the language).
>    SQL may be a bit wordier than QUEL.
>    Probably Date's statement is based on some older implementation
>    of SQL.

QUEL really IS better than SQL.  There is a large class of queries that
are easy to do in QUEL but quite difficult in SQL.  Furthermore,
there are many queries, easy in QUEL, that are utterly impossible to do in
SQL unless you do several queries using explicit temporary relations.
QUEL has much more functionality.  

QUEL is made up of simple rules from which complex queries may be built.
SQL is full of special cases, non-orthogonal constructs, and strange
restrictions.  Date recently said (unofficially, to a friend) that he
could write an SQL grammar in 5 1/2 printed pages, and a QUEL grammar in
2 pages, and QUEL clearly had more functionality.  And believe me, some
of the gotchas in SQL are very irritating!  Comparing SQL to QUEL is
like comparing C to COBOL -- you can do the same things, but one is a
lot more `powerful' than the other.

My qualifications:  I wrote a what can be loosely characterized as an
SQL-to-QUEL translation package (somewhat similar, I suspect, to what
RTI did).  By the way, the reverse translation (QUEL-to-SQL) is not 
even remotely possible.

By the way, I STRONGLY recommend Date's articles in the SIGMOD Record,
Nov. 84 (vol. 14, no. 3).  These have been reprinted in some anthology,
too.  There are two articles: one discusses criteria for evaluating
query languages, and the second shows how SQL fails those criteria, with
suggestions for improvements.  The articles are both highly entertaining.
-- 
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