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90

Databases MCQ with Answers

90) Given the basic ER and relational model which of the following is incorrect

An entity can have more than one attrbute

An attribute of an entity can be composite.

In row of a relational table, an attribute have more than one value.

In row of a relational table, an attribute can have exactly one value or a NULL value.

Answer is:

In row of a relational table, an attribute have more than one value.

Databases MCQ with Answers

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Related Databases MCQ with Answers

92) Let r be a relation instance with schema R = (A, B, C, D). We define r1 =∏ A,B,C (r) and r2 = ∏A, D(r)
Let S = r1* r2 where * denotes natural join. Given that the decomposition of r into r1 and r2 is lossy, which one of the following is TRUE?

S ⊂ r

r ∪ s = r

r ⊂ s

r*s = s

Answer is:

r ⊂ s

93) Let E1 and E2 be two entities in an E/R diagram with simple single-valued attributes. R1 and R2 are two relationships between E1 and E2, where R1 is one-to-many and R2 is many-to-many. RI and R2 do not have any attributes of their own. What is the minimum number of tables required to represent this situation in the relational model?

2

3

4

5

Answer is:

3

94) The file organization that provides very fast access to any arbitrary record of a file is

Ordered file

Unordered file

Hashed file

B-tree

Answer is:

Hashed file

95) The physical location of a record is determined by a mathematical formula that transforms a file key into a record location is :

B-Tree File

Hashed File

Indexed File

Sequential file.

Answer is:

Hashed File

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