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final_exam_tutorial

# final_exam_tutorial - NetID CS411 Database Systems Fall...

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NetID: Problem 1 ( 30 points ) Misc. Concepts For each of the following statements, indicate whether the entire statement is TRUE or FALSE by circling your choice. If you feel the statement is partially true and partially false, choose FALSE. You will get 1 . 5 points for each correct answer, –0.5 point for each incorrect answer, and 0 point for each answer left blank. 1. A mathematical definition of a relationship (as in an E/R model) is: if A and B are sets, then a relationship R is a subset of the set A B . TRUE FALSE 2. There is no formal way to specify multiple keys in an E/R diagram. TRUE FALSE 3. A “weak entity set” is not an entity set, it is a special type of relationship between two entity sets. TRUE FALSE 4. Let’s say you examined all the tuples in a relation at a particular time, and found that no two tuples have the same value for a particular attribute A. You can designate A to be a key for the relation. TRUE FALSE 5. SQL allows you to not only create a new table, but also to delete an existing table from the database. TRUE FALSE 6. In translating subclass entity sets into the relational model, the “use nulls approach” creates the fewest relations. TRUE FALSE 7. In relational algebra, the schema of R1 – R2 includes the attributes of R1 that are not attributes of R2. TRUE FALSE 8. A Theta-join is a Cartesian product operation followed by a projection operation.
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