Showing posts with label E-R diagram for online bookstore. Show all posts
Showing posts with label E-R diagram for online bookstore. Show all posts

Thursday, 31 January 2013

Define the concept of aggregation. Give two examples of where this concept is useful.

Q) Define the concept of aggregation. Give two examples of where this concept is useful.


Answer: Aggregation is an abstraction through which relationships are treated as higher-level entities. Thus the relationship between entities A and B is treated as if it were an entity C. Some examples of this are:

a. Employees work for projects. An employee working for a particular project uses various