CPSC 304 2005 MIDTERM 1 SOLUTIONS

Erdiagramsareusedforconceptualmodelingnotlogicalmodeli

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Unformatted text preview: t it. The query optimizer will come up with a declarative query execution plan b. We use ER diagrams to logically model concepts False. ER diagrams are used for conceptual modeling, not logical modeling. This is on the reminder of where we are in the introduction slide for most units. True False True False True False c. This diagram is an example of a relationship with a many to one cardinality ratio False. This is one to many. See ER diagram slides. Note that this was initially graded incorrectly, but this is the correct answer. d. Every query that can be expressed in relational algebra can be expressed as a safe query in domain relational calculus; the converse is also true True. The catch is that the queries must be safe, otherwise domain relational calculus is more expressive. See slides on DRC. True False ABàC, DàE, EàC is a minimal cover for the set of functional dependencies ABàC, DàE, ABàE, EàC. False. There’s no way to derive ABàE from the first list of dependencies False f. True e. g. An update anomaly is when it is not possibl...
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