Consider a relation r A b c d e with the following functional dependencies
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This set of Database Multiple Choice Questions & Answers (MCQs) focuses on “Functional-Dependency Theory”. Show
1. We can use the following three rules to find logically implied functional dependencies. This collection of rules is called Answer: b 2. Which of the following is not Armstrong’s Axiom? Answer: c 3. The relation employee(ID,name,street,Credit,street,city,salary) is decomposed into Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now! advertisement advertisement employee1 (ID, name) employee2 (name, street, city, salary) This type of decomposition is called Answer: d Check this: RDBMS MCQ | Programming Books 4. Inst_dept (ID, name, salary, dept name, building, budget) is decomposed into instructor (ID, name, dept name, salary) department (dept name, building, budget) This comes under Answer: d advertisement 5. There are two functional dependencies with the same set of attributes on the left side of the arrow: Answer: a advertisement 6. Consider a relation R(A,B,C,D,E) with the following functional dependencies: ABC -> DE and D -> AB The number of superkeys of R is: Answer: c 7. Suppose we wish to find the ID’s of the employees that are managed by people who are managed by the employee with ID 123. Here are two possible queries: I.SELECT ee.empID FROM Emps ee, Emps ff WHERE ee.mgrID = ff.empID AND ff.mgrID = 123; II.SELECT empID FROM Emps WHERE mgrID IN (SELECT empID FROM Emps WHERE mgrID = 123); Which, if any, of the two queries above will correctly (in SQL2) get the desired set of employee ID’s? Answer: a 8. Suppose relation R(A,B) currently has tuples {(1,2), (1,3), (3,4)} and relation S(B,C) currently has {(2,5), (4,6), (7,8)}. Then the number of tuples in the result of the SQL query: <i>SELECT * FROM R NATURAL OUTER JOIN S; i>IS: a) 2 Answer: a 9. Suppose now that R(A,B) and S(A,B) are two relations with r and s tuples, respectively (again, not necessarily distinct). If m is the number of (not necessarily distinct) tuples in the result of the SQL query: R intersect S; Then which of the following is the most restrictive, correct condition on the value of m? Answer: d 10. Suppose relation R(A,B,C,D,E) has the following functional dependencies: A -> B B -> C BC -> A A -> D E -> A D -> E Which of the following is not a key? Answer: c Sanfoundry Global Education & Learning Series – Database Management System. To practice all areas of Database Management System, here is complete set on 1000+ Multiple Choice Questions and Answers on Database Management System. Which of the following is are takes a relation which is based on functional dependencies that take into account all candidate keys in a relation?Boyce–Codd Normal Form (BCNF) is based on functional dependencies that take into account all candidate keys in a relation; however, BCNF also has additional constraints compared with the general definition of 3NF. A relation is in BCNF if, X is superkey for every functional dependency (FD) X? Y in given relation.
Which of the following functional dependencies hold for relations?Explanation: For given relation R1(A, B, C) and R2(B, D, E), functional dependencies are given only for relation R1, not for R2 And the candidate key for R1 is B, so all values must be unique in R1. To get the maximum number of tuples in output, there can be two possibilities.
Which of the following sets of attributes does not functionally determine e?Which of the following sets of attributes does not functionally determine E? Answer: ACD Yes; ACD+ = ACD, so E is not functionally determined.
Which of the following is a type of functional dependency?There are mainly four types of Functional Dependency in DBMS: Trivial functional dependency. Non-Trivial functional dependency. Multivalued functional dependency.
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