Checkpoint
Where We've Been
We must consider several issues when mapping an object view of the system to a relational database design. The early inclination is to create one-to-one mappings, but this approach usually results in too many tables.
Most one-to-one class associations can be collapsed into one relational table. This might not be the case if the association is optional.
Three common approaches to mapping inheritance to the relational model are available. One is to create a table for each class involved and a view for each subclass. Another is to collapse all of the attributes from the subclasses into a table matched to the superclass. The last is to take the attributes found in the superclass and duplicate them in each table for each ...
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