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Unformatted text preview: NetID: CS411 Database Systems Fall 2011, Prof. Zhao Department of Computer Science University of Illinois at Urbana-Champaign Midterm Examination October 13, 2011 Time Limit: 75 minutes Print your name and NetID below. In addition, print your NetID in the upper right corner of every page. Name: NetID: Including this cover page, this exam booklet contains 10 pages. Check if you have missing pages. The exam is closed book and closed notes. No calculators or other electronic devices are permitted. Any form of cheating on the examination will result in a zero grade. Please write your solutions in the spaces provided on the exam. You may use the blank areas and backs of the exam pages for scratch work. Please do not use any additional scratch paper. Please make your answers clear and succinct; you will lose credit for verbose, convo- luted, or confusing answers. Simplicity does count! Plan your time and strategy. Look through the entire exam before getting started. Problem 1 2 3 4 Total Points 30 30 22 18 100 Score Grader 1 NetID: Problem 1 ( 30 points ) Misc. Concepts For each of the following statements: for true/false choices, indicate whether it is TRUE or FALSE by circling your choice, and provide an explanation to justify; for short answer questions, provide a brief answer with clear explanation . You will get 3 points for each correct answer with correct explanations, and no penalty (of negative points) for wrong answers . For True/False questions, 1 point will be awarded for the correct answer, and 2 points for the explanation (1) Answer: True False If E is a weak entity set, then its key can only be the key attributes of Es supporting entity sets. Explain : False . The key of E can contain its own attributes as well. (2) Answer: True False In relational algebra, the six core operations are selection, projection, Cartesian product, union, intersection and difference, none of which can be written in terms of any of the other five....
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