Extended ER Features
Extended Entity Relationship (ER) Features As the complexity of data increased in the late 1980s, it became more and more difficult to use the traditional ER Model for database modelling. Hence some improvements or enhancements were made to the existing ER Model to make it able to handle the complex applications better. Hence, as part of the Extended ER Model, along with other improvements, three new concepts were added to the existing ER Model: Generalization Specialization Aggregation Generalization Generalization is the process of extracting common properties from a set of entities and create a generalized entity from it. Generalization is a "bottle-up approach" in which two or more entities can be combined to form a higher level entity if they have some attributes in common. Subclasses are combined to make a superclass. Generalization is used to emphasize the similarities among lower-level entity set and to hide differences in the schema. Example: Consider we have 3 sub e...
