midterm-w2005 - Winter 2005 COSC-3421 Midterm Test p 1 of...

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Winter 2005 COSC-3421 Midterm Test p. 1 of 16 COSC-3421 Midterm Test Family Name: Given Name: Instructor: Parke Godfrey Exam Duration: 75 minutes Term: Winter 2005 Your assignment, should you choose to accept it, is to answer the following questions to the best of your knowledge. Keep answers brief and to the point. Answers, such as yes or no should be justified by supporting argument, however. Be precise and be careful. The exam is closed-book and closed-notes. Write any assumptions that you need to make along with your answers, whenever necessary. There are five major questions. Each is worth ten points for a total of 50 points. The weight for each sub-question is indicated (or is one point by default). Regrade Policy You must not write anything on the exam paper after the exam period if it is to be considered for regrading. Write any subse- quent notes on separate paper. Regrading should be requested in writing. Write what you would like to be reconsid- ered. Note that an exam accepted for re- grading will be reviewed and regraded in entirety (all questions). Grading Box 1. 2. 3. 4. 5. Total
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Winter 2005 COSC-3421 Midterm Test p. 2 of 16 1. (10 points) E-R. Where’s the diagram?! (Exercise) Customer ( cid , name , address ) Magazine ( title , publisher , topic , frequency , url ) Pricing ( title , publisher , period , offer , price ) FK (title, publisher) refs Magazine Subscribes ( cid , title , publisher , offer , from , period ) FK (cid) refs Customer FK (title, publisher, period, offer) refs Pricing In each relation, the underlined attributes indicate the primary key. Attributes in italics (e.g., name ) are not nullable. FK stands for foreign key . (These conventions are used throughout the test.) The attribute period in Pricing tells for how many years the subscription is. The attribute frequency in Magazine tells how often the magazine is published (weekly, monthly, etc.). The attribute from in Subscribes tells when the subscription for the customer commences. a. (7 points) Draw an E-R diagram for the relational schema above. Do not add any unnec- essary elements. Do not make anything an entity that can be modeled appropriately as a relationship. Do not make anything a relationship (or an entity) that can be modeled appropriately as an attribute.
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Winter 2005 COSC-3421 Midterm Test p. 3 of 16 b. (3 points) Say that your schema additionally has Offer ( offer , period ) and Pricing is changed to Pricing ( title , publisher , period , offer , price ) FK (title, publisher) refs Magazine FK (offer, period) refs Offer ( Customer , Magazine , and Subscribes stay the same as in 1a.) Describe briefly in English how your E-R diagram (your answer in 1a) would need to be modified.
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Winter 2005 COSC-3421 Midterm Test p. 4 of 16 2. (10 points) The Relational Model / Miscellaneous. Table that motion! (Multiple Choice) Pick the one best answer for each of the following.
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