Using Data Modeler

Figure 9Many-to-Many Associations Map to Intersection TablesMapping Association Classes to Intersection TablesAn association class that links to a many-to-many association maps to an intersectiontable structure where the intersection table contains one or more additional columnsthat are not primary/foreign keys. An association class is an additional class attachedto an association that can store properties and operations shared by the twoindividual classes of the association. The reason the classes share these properties andoperations is because they cannot be stored in either of the classes. Data Modelertransforms association classes and their properties, but association class operationsare ignored by Data Modeler. In the object to data model transformation, DataModeler transforms the two classes to tables and joins them to an intersection tablewith two identifying relationships, migrating the primary keys of each individualtable to the intersection table as primary/foreign keys. Then Data Modeler adds theattributes of the association class as columns in the intersection table.20 Chapter 3 - Logical Data Modeling