Skip to Main Content
Database Modeling with Microsoft® Visio for Enterprise Architects
book

Database Modeling with Microsoft® Visio for Enterprise Architects

by Terry Halpin, Ken Evans, Pat Hallock, Bill Maclean
September 2003
Intermediate to advanced content levelIntermediate to advanced
425 pages
16h 30m
English
Morgan Kaufmann
Content preview from Database Modeling with Microsoft® Visio for Enterprise Architects
5.6 Subtyping
If the population of an object type A must always be a subset of the population of
another object type B, then A is said to be a subtype of B, and B is said to be a super-
type of A. In ORM, this is depicted visually by a solid arrow running from the subtype
to the supertype. For example, Figure 5–17 shows a fragment of a model used for a hos-
pital information system. In this model, MalePatient and FemalePatient are each sub-
types of Patient.
The main reason for introducing a subtype is to declare that specific roles are played
only by that type. For example: prostate status may be recorded only for male patients;
pregnancy counts and ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Mastering Data Modeling: A User-Driven Approach

Mastering Data Modeling: A User-Driven Approach

John Carlis
Architecting Data-Intensive SaaS Applications

Architecting Data-Intensive SaaS Applications

William Waddington, Kevin McGinley, Pui Kei Johnston Chu, Gjorgji Georgievski, Dinesh Kulkarni
Limitless Analytics with Azure Synapse

Limitless Analytics with Azure Synapse

Saranya Ravichander, Prashant Kumar Mishra

Publisher Resources

ISBN: 9781558609198