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COMP 521 F10 Final Exam Review

COMP 521 F10 Final Exam Review. 1. Which of the following is defined as a property or description of an entity. A. Relation B. Attribute C. Domain D. Selection E. Projection . Given the valid relation Instance below,.

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COMP 521 F10 Final Exam Review

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  1. COMP 521 F10Final Exam Review

  2. 1. Which of the following is defined as a property or description of an entity. A. Relation B. Attribute C. Domain D. Selection E. Projection

  3. Given the valid relation Instance below, Which of the following sets of attributes cannot be a candidate key? A. A1 B. A3 C. <A4, A5> D. <A3, A4> E. <A2, A3> Which attribute can you deduce is a candidate key? A. A1 B. A2 C. A3 D. A4 E. None of the above

  4. A relation R(A, B, C), represents a relationship between two entities with keys A and B respectively. It also has the functional dependences A? B and B ? A. What does such a pair of dependences mean? A. There is total participation of both entities B. The relationship is one-to-one C. The two entity sets form a disjoint cover D. The relationship is many-to-many E. The relation cannot be in BCNF

  5. Which of the following SQL features supports logical data independence? A. Its portability across DBMSs B. The fact that it is relationally complete C. It’s declarative semantics D. It’s support of ‘views’ E. All of the above

  6. Which of the following database properties states that, once committed, data should persist in the database, even if the system crashes. • A. Atomicity • B. Buffer Writes • C. Consistency • D. Durability • E. Equality

  7. Which of the following most likely explains the result set of the SQL query: SELECT DISTINCT S.name FROM Student S WHERE S.id IN ( SELECT C.sid FROM Class C GROUP BY C.sid HAVING COUNT (*) >= ALL ( SELECT COUNT (*) FROM Class C2 GROUP BY C2.sid)) A. Names of students taking the class with the largest enrollment B. Names of students taking the most classes C. Names of students taking one or more classes D. Names of all students taking no classes E. Names of all students

  8. What results from the following schedule: R2(X), R2(Y), W2(X), R1(X), R1(Y), W2(Y), W1(X) A. A write-read conflict B. A read-write conflict C. A write-write conflict D. No conflicts, equivalent to T1, T2 E. No conflicts, equivalent to T2, T1

  9. 18. Which of the following about record ids is false? A. They uniquely identify a particular record B. They identify the disk address of the page containing the record C. Given one, only one I/O is required to read the associated record into memory D. They determine the page buffer where a record is stored in main memory E. They appear frequently in indices

  10. 46. Which of the following is true after inserting 19 and 20 into the B+-tree shown? • A. The tree will split and gain a level • B. All nodes of the tree will be filled • C. The tree’s structure is unchanged • D. The resulting tree is identical to the original • E. The tree looses a level

  11. Questions?

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