GATE CSE 2012 | GATE CSE Year Wise Previous Years Questions

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GATE CSE 2012

MCQ (Single Correct Answer)

-0.3

Given the basic $$ER$$ and relational models, which of the following is INCORRECT?

An attribute of an entity can have more than one value

An attribute of an entity can be composite

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

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

GATE CSE 2012

MCQ (Single Correct Answer)

-0.3

Which of the following is TRUE?

Every relation in $$3NF$$ is also in $$BCNF$$

A relation $$R$$ is in $$3NF$$ if every non-prime attribute of $$R$$ is fully functionally dependent on every key of $$R$$

Every relation in $$BCNF$$ is also in $$3NF$$

No relation can be in both $$BCNF$$ and $$3NF$$

GATE CSE 2012

MCQ (Single Correct Answer)

-0.3

Which of the following statements are TRUE about an SQL query?

P: An SQL query can contain a HAVING clause even if it does not have a GROUP BY clause
Q: An SQL query can contain a HAVING clause only if it has a GROUP BY clause
R: All attributes used in the GROUP BY clause must appear in the SELECT clause
S: Not all attributes used in the GROUP BY clause need to appear in the SELECT clause

P and R

P and S

Q and R

Q and S

GATE CSE 2012

MCQ (Single Correct Answer)

-0.6

Suppose R₁ (A, B) and R₂ (C, D) are two relation schemas. Let r₁ and r₂ be the corresponding relation instances. B is a foreign key that refers to C in R₂. If data in r₁ and r₂ satisfy referential integrity constraints, which of the following is ALWAYS TRUE?

$$\prod_{B}(r_{1})- \prod _{C}(r_{2})= \varnothing$$

$$\prod_{C}(r_{2})- \prod _{B}(r_{1})= \varnothing$$

$$\prod_{B}(r_{1}) = \prod _{C}(r_{2})$$

$$\prod_{B}(r_{1}) - \prod _{C}(r_{2}) \neq \varnothing$$

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