hw1KEY - COP 4710 Database Systems Fall 2009 Homework #1...

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1. (20 points – 5 points each) Construct an E-R diagram (ERD) for each of the following “real-world” scenarios. Assume no additional constraints, other than those which are explicitly stated, hold in each case. The real world that is to be modeled is a university and the database is to contain information about professors (identified by SSN) and courses (identified by a courseid). Professors teach courses. (a) Professors can teach the same course in several different semesters, and each offering must be recorded. 1 COP 4710 – Database Systems – Fall 2009 Homework #1 – 115 points - Due: In class Thursday September 24 th . NO LATE ASSIGNMENTS ACCEPTED Answer each of the following questions completely. Make sure that your answers are neatly written and very readable . Points will be deducted if your assignment is not presented in a neat format. For example, don’t turn it in on notebook paper torn out of a spiral notebook. KEY professors courses ss# cid teac h semeste old style teach professors ss# courses cid semester new style
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(b) Every professor must teach some course. (c) Every professor teaches exactly one course (no more, no less). 2 professors courses ss# cid teac h old style teach professors ss# courses cid semester new style professors courses ss# cid teac h old style teach professors ss# courses cid semester new style
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(d) Every professor teaches exactly one course (no more, no less) and every course must be taught by some professor. 2. (15 points – 5 points each) In each problem below a real-world situation is described and modeled using an ERD. In each case determine if the ERD correctly models the situation which is described and if it does not, draw a correct version. (a) Entity sets: employee, customer, items. Relationship sets: sells (an employee sells items), buys (a customer buys items). Constraints: (1) every employee must sell an item, but every item does not need to be purchased, (2) not every customer necessarily buys an item. No – not correct, total participation not indicated 3 buys sells item employee customer sel buy old style item employee customer new style professors courses ss# cid teac h old style teach professors ss# courses cid semester new style
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(b) Given the entity sets of students and restaurants . Assume that students eat-at certain restaurants. Any student can eat in any restaurant (including none of
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This note was uploaded on 11/01/2009 for the course CS cop4710 taught by Professor Dr. mark llewellyn during the Fall '09 term at University of Central Florida.

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hw1KEY - COP 4710 Database Systems Fall 2009 Homework #1...

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