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21. If the decomposition is able to represent all the facts about the relation then such a decomposition is called as?
a. Lossless decomposition
b. Lossy decomposition
c. Insecure decomposition
d. Secure decomposition
Answer: (a).Lossless decomposition

22. A domain whose elements are indivisible is called as ______
a. Unique domain
b. Proxy domain
c. Atomic domain
d. Multiple domain
Answer: (c).Atomic domain

23. If all the domains are atomic then the relational schema is in ________ normal form
a. 1
b. 2
c. 3
d. 4
Answer: (a).1

24. State true or false: Composite attributes have non-atomic domains.
a. True
b. False
c. May be
d. Can't say
Answer: (b).False

25. State true or false: Redundancy is desired in a relational schema
a. True
b. False
c. May be
d. Can't say
Answer: (b).False

26. An instance of a relation that satisfies all real world constraints is known as?
a. Proper relation
b. Ideal relation
c. Perfect relation
d. Legal relation
Answer: (d).Legal relation

27. If K → R then K is said to be the _______ of R
a. Candidate key
b. Foreign key
c. Super key
d. Domain
Answer: (c).Super key

28. X → Y holds on a schema k(K) if?
a. At least one legal instance satisfies the functional dependency
b. No legal instance satisfies the functional dependency
c. Each and every legal instance satisfies the functional dependency
d. None of the mentioned
Answer: (c).Each and every legal instance satisfies the functional dependency

29. X→ Y is trivial if?
a. X ⊂ Y
b. Y ⊂ X
c. X ⊇ Y
d. None of the mentioned
Answer: (a).X ⊂ Y

30. Which of the following is not a condition for X→ Y in Boyce codd normal form?
a. X → Y is trivial
b. X is the superkey for the relational schema R
c. Y is the superkey for the relational schema R
d. All of the mentioned
Answer: (c).Y is the superkey for the relational schema R

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