[net.database] semantics of QBE

Dale@tektronix.UUCP (01/30/86)

	I am looking for a statement of the formal semantics of QBE. I
	have read the paper "Query-by-Example: a data base language" by
	M.M. Zloof (IBM Syst. J., #4, 1977) which is one of the early
	published descriptions of QBE. That paper presents QBE by
	means of (what else!) examples. That's sufficient for the easy
	cases, but I'm uncertain of the meaning of queries involving
	aggregates or (in Ingres terminology) aggregate functions.
	And queries that involve joins on sets are completely unclear
	to me.

	There is a paper entitled "Algorithm for Processing Query by
	Example" by Niebuhr et al (IBM Tech. Disc. Bull., vol. 19 #2)
	which helps a little, but assumes the reader already understands
	the semantics.

	Anyway, any pointers to papers will be muchly appreciated.

	Dale Brayden
	Scientific Computer Center, DS 50-454
	Tektronix, Inc.
	P.O. Box 500
	Beaverton, OR  97077

johnl@ima.UUCP (02/04/86)

/* Written  1:05 pm  Jan 30, 1986 by Dale@tektronix in ima:net.database */
> I am looking for a statement of the formal semantics of QBE.

QBE turned into a product.  Ask your IBM salesman for "Query-by-Example
Terminal User's Guide," SH20-2078.  It is as close to a formal definition
as there seems to be, and has reasonable syntax charts and definitions.

John Levine, ima!johnl

herr@infbs.UUCP (02/05/86)

Here we have a diploma thesis about "Formal Semantics of QBE"
but it is in german. Are you interested anyway ?

Institut fuer Informatik
TU Braunschweig
Postfach 3329
D-3300 Braunschweig
Germany