CMPSC431W_HW1.pdf - 1[10 points What is a data model What...

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1. [10 points] What is a data model? What is the relational data model? Data model is used to describe stored data that hides low-level storage using collection of high level constructs. Relational Data model describes relation using a row and column table. 2. [10 points] What is logical data independence? Please explain. Logical Data independence allows changes in logical data structure without letting the users know about it. 3. [60 points] A university database contains information about professors (identified by emp_id) and courses (identified by course_id). Professors teach courses. Each of the following situations concerns the Teaches relationship set. For each situation, draw an ER diagram that describes it (assuming no further constraints hold). a) Professors can teach the same course in several semesters, and each offering must be recorded. b) Professors can teach the same course in several semesters, and only the most recent such offering needs to be recorded. (Assume this condition applies in all subsequent questions.)
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