GATE CSE 2012 | GATE CSE Year Wise Previous Years Questions

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?

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

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

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

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

GATE CSE 2012

MCQ (Single Correct Answer)

-0.6

Consider the following transactions with data items P and Q initialized to zero:

T₁ : read (P) ; 
     read (Q) ; 
     if P = 0 then Q : = Q + 1 ; 
     write (Q).

T₂ : read (Q) ; 
     read (P) 
     if Q = 0 then P : = P + 1 ; 
     write (P).

Any non-serial interleaving of T₁ and T₂ for concurrent execution leads to

a serializable schedule

a schedule that is not conflict serializable

a conflict serializable schedule

a schedule for which precedence graph cannot be drawn

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 $$3NF$$

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