ERD -casestudies - Case Study 1 A university database contains information about professors(identified by social security number or SSN and

ERD -casestudies - Case Study 1 A university database...

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Case Study 1 A university database contains information about professors (identified by social security number, or SSN) 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 that no further constraints hold). 1. Professors can teach the same course in several semesters, and each offering must be recorded. 2. 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) 3. Every professor must teach some course. 4. Every professor teaches exactly one course. 5. Every professor teaches exactly one course and every course must be taught by some professor. 6. Now suppose that certain courses can be taught by the team of professors jointly, but it is possible that no one professor in a team can teach the course. Model this situation introducing additional entity set and relationship sets it necessary. Case Study 2 Consider the following information about the university data base 1. Professors have an SSN, a name, an age, a rank and a research specialty. 2. Projects have a project number, a sponsor name, a starting date and ending date and the budget. 3. Graduate students have an SSN, a name, an age and a degree program (MS or PhD). 4. Each project is managed by one professor (known as the project’s principal investigator). 5. Each project is work on by one or more professors (known as the project’s co investigators). 6. Professors can manage and /or work on multiple projects. 7. Each project is work on by one or more graduate students (known as the project’s research assistants) 8. When graduate student work on a project, a professor must supervise their work on the project. Graduate students can work on multiple projects, in which case they will have supervisor for each one (potentially different). 9. Departments have a department no., a department name and main office. 10. Departments have a professor known as a (chairman) who runs the department. 11. Professors work in one or more departments, and for each department that they work in, a time percentage is associated with their job. 12. Graduate students have one major department in which they are working on their degree. 13. Each graduate student has another, more senior graduate student (known as a student advisor) who advises him or her on what courses to take. Design and draw an ER diagram for the following collection of data. Use only the basic ER model here, i.e., entities relationships and attributes. Be sure to indicate any key and participation constraints. Case Study 2 A company database needs to store information about employees (identified by small SSN, with salary and phone as attributes) , departments (identified by DNO, with D_NAME and budget as attributes, and children of employees (with name,
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age as attributes). Employees work in departments, each department is managed by
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  • Summer '12
  • Entity-relationship model, entity

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