cs411-s10-final questions only - NetID: CS411 Database...

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NetID: CS411 Database Systems Spring 2010, Prof. Chang Department of Computer Science University of Illinois at Urbana-Champaign Final Examination May 14, 2010 Time Limit: 180 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 16 pages. Check if you have missing pages. The exam is closed book and closed notes. You are allowed to use scratch papers. 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 make your answers clear and succinct; you will lose credit for verbose, convo- luted, or confusing answers. Simplicity does count! Each problem has different weight, as listed below– So, plan your time accordingly. You should look through the entire exam before getting started, to plan your strategy. Problem 1 2 3 4 5 6 7 Total Points 22 16 11 10 12 15 14 100 Score Grader 1
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NetID: Problem 1 ( 22 points ) Misc. Concepts For each of the following statements, indicate whether it is TRUE or FALSE by circling your choice, and provide an explanation to justify. You will get 2 points for each correct answer with correct explanations, and no penalty (of negative points) for wrong answers . (1) An E-R diagram will translate uniquely to a relational schema. (2) In an E-R diagram, an entity will translate to a table in the relation model, while a relationship will translate to a join between tables. (3) We can consider relational algebra as a query language. (4) The basic operators in relational algebra are π,σ,ρ, on , , - . (5) In SQL, we can only use aggregate functions where there is a Group-By clause. (6) In rule-based optimization, a commonly used heuristic rule is to push projection down, to reduce the number of columns early on. (7) In optimizing join queries, we choose to assume only left-deep join trees, because such trees are most efficient. (8) When we program a database transaction, we can use the “Abort” command to rollback a transaction that cannot be successfully completed.
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This note was uploaded on 02/17/2012 for the course CS 411 taught by Professor Winslett during the Fall '07 term at University of Illinois at Urbana–Champaign.

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cs411-s10-final questions only - NetID: CS411 Database...

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