Objectives

Create an external DTD that dictates a relational model-like data structure for XML documents.

Description

We are going to continue on with the previous assignment's suggested context: courses. In addition to recording information for courses, the model is now broadened to include students, Course Registration Number (CRN), and prerequisites. You are going to use DTD to enforce certain data requirements in order to model the following transaction processing:

- A Student which contains:
o email address
o first name
o ID (primary key, so should be an attribute, ID)
o last name
o phone number

- A Course which contains:
o credits
o description
o number (primary key, so should be an attribute, e.g. COMP 2899, ID)
o name
o a grouped list of prerequisite courses (references to other courses, IDREFS)

- CRN which contains:
o ID (primary key, so should be an attribute, e.g. 78645, ID)
o course number (foreign key, so should be an attribute, IDREF)
o total number of students
o end date
o start date
o cost
o instructor name

- Student-CRN which contains
o student ID (foreign key, so should be an attribute, IDREF)
o CRN (foreign key, so should be an attribute, IDREF)