🚀 go-pugleaf

DEPARTMENT OF COMPUTER SCIENCE
UNIVERSITY OF WATERLOO
SEMINAR ACTIVITIES

MASTER'S ESSAY PRESENTATION

                    -Thursday, April 27, 1989

Mr.  Marc  Dionne,  graduate student, Dept. of Computer
Science, University of Waterloo will present a Master's
Essay  Presentation on ``Optimizing SQL Queries Against
VAX DBMS Databases.''

TIME:                 1:30 PM

ROOM:              DC 1302

ABSTRACT

The relational model appears to be the state of the art
for  current  commercially available database products,
but systems based on other models have been widely used
for a number of years.  It would be highly desirable to
be  able  to  access  these different databases using a
common  query  language.   Given  the widespread use of
SQL, it constitutes a good choice for this purpose.

Some  form  of conversion has to take place between the
user  and  system levels to allow access to the network
database  with a relational query language.  We present
the approach used to build an interface between SQL and
a specific network database system, VAX DBMS.  From the
DBMS   schema  we  create  a  relational  view  of  the
database,  upon  which  the  user can base his queries.
Given   a   query,   the  software  generates  possible
strategies  for  evaluation,  and  determines which one
appears to be the most efficient. This strategy is then
used   to   evaluate   the   query,   using  DBMS  data
manipulation commands, and output is produced according
to the specifications of the query.