Database Systems (CMU) Lab.

Laboratory Six (Exercise 05)

Objectives of this Laboratory:

E-R Diagram.

  1. It is a group project (5 students per group, you can form your own group within the SAME laboratory class).
  2. Every student must submit his/her own file(s) to CTE, even thought the file(s) is/are likely the same for all students within the same group.
  3. On the front page of the file, please indicate the name of each group member, and also indicate the contribution of each member. (E..g. for a group with five members, each member’s contribution should be 20%)
  4. This group project is also your exercise 05, you should submit this exercise to CTE on or before week 7.

Create the complete ER schema for your E-Commerce database from the specification given in Exercise 1 (Check out the detail from Exercise 05 of the CTE WEB). Note that the specification is from a user's point of view, and hence does not tell you all of the keys (primary and alternate), all of the relationships, and the arity of relationships, etc. You should identify them.

Make reasonable assumptions to make the specification complete. Explicitly state all your assumptions. EVERY construct in your ER schema should be substantiated by either the specification above or your explicit assumptions.

Make sure you identify all of the following:

  • the entity types (identify weak entities)
  • the attributes in each entity type (identify it also as either single-valued/multi-valued, derived, simple/composite, etc). Leave the attributes out of the diagram. Instead, list each entity in a textual form, and beneath each one, list its attributes.
  • the relationship types (identify the roles, the cardinality constraints, and participation constraints)

Use the ER diagramming notations to draw your schema. Turn in your ER schema in a file named ER.gif, and the attribute list in a text file named ER.txt.

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