Relationships: Improved Integrity for Relational-Based Computer Aided Design/Computer Aided Manufacturing/Geographic Information Systems
Original Publication Date: 1996-Dec-01
Included in the Prior Art Database: 2005-Apr-01
Publishing Venue
IBM
Related People
Abstract
Disclosed is a method for modeling complicated real world relationships in Geographic Information Systems. The solution is an application of the entity-relationship model to the instance level of a relational database system. It provides robust insertion, update, and deletion integrity beyond ordinary relational database technology. Four types of relationships are presented: o one-to-one o one-to-many o many-to-one o many-to-many
Relationships: Improved Integrity for Relational-Based
Computer Aided
Design/Computer Aided Manufacturing/Geographic Information Systems
Disclosed is
a method for modeling complicated real world
relationships in Geographic Information Systems. The solution is an
application of the entity-relationship model to the instance level of
a relational database system. It
provides robust insertion, update,
and deletion integrity beyond ordinary relational database
technology. Four types of relationships
are presented:
o
one-to-one
o
one-to-many
o
many-to-one
o
many-to-many
The evolution
of Geographic Information Systems (GIS), Computer
Aided Design (CAD), and Computer Aided Manufacturing (CAM) has
required that information be stored and retrieved from
non-proprietary databases within an
enterprise. This information is
very complex. In particular, the relationships between real-world
objects modelled by GIS/CAD/CAM are
difficult to represent in most
relational databases. These relationships can be system defined or
user defined. For a GIS, examples
include:
o
A house with a mailbox
o
An ocean with ships and ports
o
A port with ships and containers
o
area features and their boundaries
o
boundaries and their edges
o
parent features and their dependent features
o
layers and their features
The trend for
modeling these complex relationships has been the
adoption of object oriented databases and software by many
GIS/CAD/CAM systems. Businesses have not
benefitted from this
direction, however, as most enterprises
use relational databases.
The problem
with relational databases is that they do not
provide enough tools to model the complex relationships that exist in
the real world. The major relational
tools (referential integrity,
indirect tables and foreign keys) are too basic. A GIS/CAD/CAM
system that forced users to be aware of these tools would be
extremely unwieldy. What is needed is a
unified approach to
modelling complex, real world relationships between instances of data
that uses an underlying relational database to preserve the
enterprise's investment.
The name of
the tool is relationships. A
relationship is an
interdependence between two instances of GIS/CAD/CAM data. For
example, there could be a relationship between a telephone pole and a
road. Relationships can only exist at
the instance level; they
cannot exist between the "HEIGHT" attribute of a telephone pole and
the "WIDTH" attribute of a
road.
Relationships
can be system- or user-defined. Examples
of
system-defined relationships that are common to a GIS are:
o
area features and their boundaries
o
boundaries and their edges
o
parent features and their dependent features
o
layers and their features
Examples of user-defined relationships are:
o
A house with a mailbox
o
An ocean with ships and ports
o ...