| 31. | Which of the following is used to express database consistency? |
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Answer: (d).All of the mentioned
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| 32. | Which of the following is not a condition for the third normal form in the case of X→Y? |
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Answer: (d).Each attribute in X-Y is a candidate key for R
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| 33. | F+ is called as the ________ of F |
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Answer: (a).Closure
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| 34. | State true or false: A functional dependency must first satisfy the second normal form to satisfy the third normal form. |
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Answer: (a).True
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| 35. | State true or false: The fourth normal form does not exist and it is instead called as the BCNF. |
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Answer: (b).False
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| 36. | A functional dependency f on R is _______ by a set of functional dependencies F on r if every instance of r(R) that satisfies f also satisfies F. |
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Answer: (c).Logically implied
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| 37. | If F is a set of functional dependencies, then the closure of F is denoted by? |
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Answer: (c).F+
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| 38. | If a functional dependency is reflexive, B is a subset of A and A is the set of attributes, then |
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Answer: (b).A→B holds
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| 39. | State true or false: Armstrong’s axioms allow us to generate all F+ for any given F |
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Answer: (a).True
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| 40. | Armstrong axioms are called sound because? |
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Answer: (d).They cannot generate incorrect functional dependencies
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