Conceptual Schema and Relational Database Design

This book stands by itself in the database design world which is mired down in the Entity-Relationship paradigm. In my mind, Terry Halpin has the most powerful technique for going from "hey I think we need a database" to a relational-table structure that has half a chance of satisfying the original loosely described need. The Object Role Modeling (ORM) approach described in this book is embodied in software that Microsoft is giving away for free! (VisioModeler 3.1 from Microsoft's download site. Search in the Visio 2000 Enterprise downloads. Check out ERWIN which will cost you thousands and then use Visiomodeler.) ORM diagrams are pictures which, like control system block diagrams, are exact mathematical statements describing interrelated data. They deal with data a "fact at a time", the way the "rest of us" do. These diagrams are simple enough to use as discussion points customers who could probably care less about the underlying database structures. One indication of how straight forward ORM is: high school kids in Australia use ORM diagrams to design databases in a computer science curriculum. To work through the modeling and design task Halpin describes the Conceptual Schema Design Procedure (CSDP) which takes care of all the necessary theoretical stuff. The book is out of print but Halpin has another in the mill titled, "Information Modeling and Relational Databases: From Conceptual Analysis to Logical Design", see Morgan Kaufmann Publishers web site mkp.com. Until then, Halpin's web site at orm.net and InConcept's Journal Of Conceptual Modeling at inconcept.com provide a wealth of ORM information. One caution when jumping into ORM. Take some time to get used to the ORM terminology and the very different approach to modeling at the fact level. You may be handicapped by the all pervasive entity-relationship notion and your knowledge of how to construct database tables. In the end you will be so much better off!

Too bad it's out of print. Too bad InfoModeler ... based on ORM ... is not sold anymore. Visio just lets you draw pictures. InfoModeler let you key in FORML statements .. ORM syntax .. and build database schemas.But a lot of study of ORM allows me to build a OO class hierarchy .. and has greatly enhanced my productivity.Dr. Halpin .. if you read this ... know that there are programmers out there you have helped immensely. I'm using your techniques in n-tier web applications as I write this.

I think this book is one of the very best resources for database design available. As a professional database designer, I have seen numerous examples of database applications that don't really help the users run their business more efficiently. The root cause of the problem is poor database design.The heart of every business application is a database, and the key to creating a good database is accurately capturing business requirements and turning those business requirements into a workable system design.This book will teach you a method called "Object Role Modeling" (ORM) for gathering requirements and creating a design. In ORM, you concentrate on business facts (e.g. "Commission is allocated to Salesman based on Percentage") instead of database entities and attributes. This fact-based approach allows the designer to communicate with the user in a way that makes sense to the user. A collection of business facts is called a "conceptua! l model". ORM provides an algorithm that automatically generates a properly normalized ER model from a conceptual fact based model.Most other books that deal with database design focus on logical issues like normalization, key structures, etc. The problem is that logical issues don't matter if you can't accurately capture the business requirements using formal and managable method.Conceptual Schema and Relational Database Design teaches you how to capture the facts using ORM. The book explains how the logical issues can be automatically resolved once you have a valid conceptual model.One thing I especially like about the book is the large number of sample problems. Each section has a list of questions, and the answers to the odd numbered questions are in the back of the book.If you need to build a system for business users, this is the book for you. If you are already an experienced data modeler, this book will help you communicate better with your users, ! and ensure success on your project. If you haven't done da! ta modeling before, this book presents one of the very best methods.