that4loopgirl

The features of the E – R includes specialization, generalization, higher level & lower level entity sets, attribute inheritance, and aggregation. 1. Specialization An entity set may have subgrouping of entities that are different from other entity set in some form. These entity grouping can be represented using E – R model. The process of describing subgrouping within an entity set is known as Specialization . An entity set may be specialized by more than one distinguish feature. For example, consider an entity set named person , having attributes name , street , and city . The person can be classified as: customer or employee . A set of attributes that includes all the attributes of entity person are described by each of these person type. For example, customer entities may be further described by attribute customer_id , and the employee entities can be further described by attributes employee_id, employee_salary. Consider another example, suppose bank decides to d