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database design - Review this ER Diagram?

问题描述:

You have been asked to design a database for the university

administartion, which records the following information:

  • All students necessarily have a unique student ID, a name, and, a university email address.
  • Each student is also either an undergraduate or a graduate student.
  • Each graduate student has an adviser.
  • Each undergraduate student has a major.
  • Students take courses. A student may take one, multiple, or, no courses.
  • Each course has a course number, name, and, days of the week the course is scheduled.

  • Is my ER Diagram correct?
  • Should WeekDay be an entity? Why or Why not? Do you think that it should be a multi-valued attribute? Why?
  • Should Undergraduate Student and Graduate Student be separate entities? Why or Why not?

Please, ignore the absence of cardinalities for the moment.

网友答案:

Making Weekday an entity would imply that you would make your own table for weekday. That, in general, is only useful if weekday should hold further attributes. In terms of the simple scenario you provided, making weekday an entity is redundant, and would only bloat your design. Of course, this MIGHT change depending on whether you want to extend your design in the future.

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