Addendum to CPS 430/542 Homework #3

Assigned: September 20
Due: September 27, 4:30pm, in class

(10 points) Find a site on the WWW for which there is obviously an underlying database system. Attempt to view it in the light of what we have learned in CPS 430/542 so far. Present the site as an application of database systems. Your answer should contain:

  1. the URL of the site you found;
  2. a 2-paragraph (500 words in total) description of the database functionality (i.e, what does it model?, what does it not model?, who are the users?, what kinds of queries does it supports? and so on); and
  3. your version of what the site's E/R diagram probably looks like. Your answer should provide at least

    1. 4-5 entity sets,
    2. 4-5 relationships,
    3. one example of inheritance, and
    4. (preferably) one example of weak entity sets.

(i) and (ii) are required. (iii) and (iv) are required if they arise naturally in the site you choose. In other words, your example of inheritance or weak entity sets should not be artificial just to satisfy the requirements. If inheritance and weak entity sets do not naturally arise in the site, state clearly why you think it is too unnatural for the application to model inheritance or weak sets.

Also, your relationships should provide a variety of possibilities: many-many, many-one, and one-one. Your attributes should also come from a mix of backgrounds (strings, integers, floats, composite structures, such as addresses, dates, and so on). In short, your design should be rich in all these goodies. Underline key attributes, include appropriate arrowheads, specify any domain-specific constraints or double-border any weak sets and supporting relationships.


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