July 2010
Intermediate to advanced
976 pages
30h 19m
English
Content preview from Information Modeling and Relational Databases, 2nd Edition
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Chapter Notes
By depicting each role as a box associated with a table column, Object-Role Modeling enables uniqueness constraints to be portrayed in a natural way where the impact of the constraint on populations is immediately apparent. Entity Relationship modeling (ER) and UML depict internal uniqueness constraints on associations using a variety of notations for “cardinality constraints” or “multiplicity constraints”, as discussed later. ER offers graphical support for some uniqueness constraints on attributes, but UML does not. Neither ER nor UML offers any significant support for external uniqueness constraints.
Object-Role Modeling makes minimal use of the notion of functional dependency, but this notion is central to many other methods. ...