ok, the book I am reading discusses this type of query:
SELECT p.pname
FROM P, SH, S
WHERE P.pnum = SH.pnum

As one of my first encounters with SQL (The RDBMS used is MySQL 5.1),
my colleague and I have designed the following (it's a part of a
catalog system for a museum):
We have an "attachments" table, which can refer to "works_of_art",

vadlo (www.vadlo.com) - great search engine and borwser for biology
methods and databases.

how correct is the following diagram showin g modules of a
DBMS ...????
http://i529.photobucket.com/albums/dd339/aarklon/5.jpg

BCNF
 the following is the definition is the definition of BCNF , which i
saw in a schaum series book
 1) The relation is 1 N.F

This is not a theory question by any means, but perhaps there is someone
hanging out here who is able to speak with authority on SQL.  We are
trying to figure out the justification for why a BEFORE trigger should
be prevented from doing any updates.  The wording we're looking at ...

I can not find a definition for "proper superkey".  I have found
"superkey", but not "proper superkey".
Sincerely,
Gene Wirchenko

I have read that data mining is the process used to find new ,hidden
or un expected patterns in the data to predict the future of the
business & that data mining is based on various statistical
techniques .

I have something like:
entity (id, live_version_id NULL, preview_version_id NULL)
version (id, parent_entity_id)
where version.parent_entity_id must be a valid entity.id, and that

Thanks to Brian S for reminding about Codd's book.  On the question of
view updateability, I'm interested in comments about this quote from
page 294: