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  1. #1
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    Jul 2013
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    Question Database modelling need answers for this

    Suppose for a college database, there was a Course entity, which specified name, id, description, etc. Later we needed to specify location, time, semester, etc. We decided to create a Class entity. This new entity included everything what was in the Course entity plus added all other data. Also at first we had a Student entity to represent all students in the college. Later we decided to be more specific and to further describe students as full time or part time. Where is generalization and where is aggregation in these two cases? Why?

  2. #2
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    Jul 2013
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    A university consists of a number of departments, department will be identified by department no, its respective name, number of course it offers. Each department offers several courses, each of the course is identified by its respective course code, course name, and its respective module it belongs to. A number of modules make up each course, each of the module is identified by its module code, module name, credit for each module. Students enrol in a particular course and take modules towards the completion of that course, students will have their student id, student name, department they belongs to, course they registered for, module they study. Each module is taught by a lecturer from the appropriate department, and each lecturer tutors a group of students, here each of the lecture is identified by their lecture number, department they belongs to, course and module they are teaching. Draw an ERD showing the description above.

  3. #3
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    Feb 2004
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    Quote Originally Posted by fariha2009 View Post
    Suppose for a college database, there was a Course entity, which specified name, id, description, etc. Later we needed to specify location, time, semester, etc. We decided to create a Class entity. This new entity included everything what was in the Course entity plus added all other data. Also at first we had a Student entity to represent all students in the college. Later we decided to be more specific and to further describe students as full time or part time. Where is generalization and where is aggregation in these two cases? Why?
    The generalization is at (or more accurately just after) 0x0020. The Aggregation only occurs in the queries, signaled by the use of an aggregate function.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

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