Database Reference
In-Depth Information
CHAPTER 9
SEMANTIC DATA MODEL TO
RELATIONAL DATA MODEL
CHAPTER OBJECTIVES
•
Examine the data model transformation method in detail
•
Understand the circumstances under which this method must be used
•
Study the mapping of components from the semantic to the relational model
•
Specifically, learn the transformation of relationships
•
Finally, compare the two models and check out the results of transformation
Toward the end of Chapter 8, we indicated that either of two methods might be
used for creating a relational data model. Model transformation method is one of
these two methods. This method is a straightforward way of examining the compo-
nents of your semantic data model and then transforming these components into
components of the required relational data model.
Two techniques were presented for creating a semantic model. A semantic model
is a generic model. The object-based data modeling technique produces a semantic
model by starting out with business objects that are of interest to an organization.
The more popular technique, the entity-relationship data modeling technique, also
produces a semantic model by adopting a natural way of looking at information
requirements. For a given set of information requirements, both techniques produce
similar semantic models with comparable components. You know how the compo-
nents of an object-based data model maps to the components of the entity-
relationship data model.
In this chapter, you will study the transformation of the object-based data model
into the relational data model. It will not be necessary to repeat the discussion to
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