Ludwig-Maximilians-Universität München, Institut für Informatik
Technical Report 93-08
- TITLE:
-
Object-Oriented Querying of Existing Relational Databases
- DATE:
-
May 1993
- AUTHORS:
- Daniel A. Keim
- Hans-Peter Kriegel
- Andreas Miethsam
- Institut für Informatik
- Universität München
- Leopoldstr. 11B
- D-80802 München (Germany)
- KEYWORDS:
-
object-oriented database systems and query languages, relational database
systems, schema enrichment, schema transformation, query translation
- ABSTRACT:
-
In this paper, we present algorithms which allow an object-oriented querying
of relational databases. Our goal is to provide an improved query interface
for relational systems with better query facilities than SQL. This seems to
be very important since, in real world applications, relational systems are
most commonly used and their dominance will remain in the near future. To
overcome the drawbacks of relational systems, especially the poor query
facilities of SQL, we propose a schema transformation and a query translation
algorithm. The schema transformation algorithm uses additional semantic
information to enhance the relational schema and transform it into a
corresponding object-oriented schema. If the additional semantic information
can be deduced from an underlying entity-relationship design schema, the
schema transformation may be done fully automatically. To query the created
object-oriented schema, we use the Structured Object Query Language (SOQL)
which provides declarative query facilities on objects. SOQL queries using
the created object-oriented schema are much shorter, easier to write and
understand and more intuitive than corresponding SQL queries leading to an
enhanced usability and an improved querying of the database. The query
translation algorithm automatically translates SOQL queries into equivalent
SQL queries for the original relational schema.
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Robert Stabl
(28.11.1994)