ISRO CS 2015

Question 21

Let R = (A, B, C, D, E, F) be a relation schema with the following dependencies C->F, E->A, EC->D, A->B. Which of the following is a key of R?

• CD
• EC
• AE
• AC

Question 22

If D₁, D₂...D_n are domains in a relational model, then the relation is a table, which is a subset of

• D₁⊕D₂⊕...⊕D_n
• D₁xD₂x...xD_n
• D₁∪D₂∪...∪D_n
• D₁∩D₂∩...∩D_n

Question 23

Consider the following relational schema:

Suppliers(sid:integer, sname:string, city:string, street:string)
Parts(pid:integer, pname:string, color:string)
Catalog(sid:integer, pid:integer, cost:real)

Consider the following relational query on the above database:

SELECT S.sname
    FROM Suppliers S
        WHERE S.sid NOT IN (SELECT C.sid
                            FROM Catalog C
                            WHERE C.pid NOT IN (SELECT P.pid  
                                                FROM Parts P
                                                WHERE P.color<> \'blue\'))

Assume that relations corresponding to the above schema are not empty. Which one of the following is the correct interpretation of the above query?

• Find the names of all suppliers who have supplied a non-blue part.
• Find the names of all suppliers who have not supplied a non-blue part
• Find the names of all suppliers who have supplied only non blue parts.
• Find the names of all suppliers who have not supplied only non-blue parts.

Question 24

Consider the following schema:

Emp (Empcode, Name, Sex, Salary, Deptt)

A simple SQL query is executed as follows:

SELECT Deptt FROM Emp
WHERE sex = \'M\'
GROUP by Dept
Having avg (Salary) > {select avg (Salary) from Emp}

The output will be

• Average salary of male employee is the average salary of the organization
• Average salary of male employee is less than the average salary of the organization
• Average salary of male employee is equal to the average salary of the organization
• Average salary of male employee is more than the average salary of the organization

Question 25

Given the following expression grammar:

E → E ∗ F ∣ F + E ∣ F
F → F − F ∣ id

Which of the following is true?

• * has higher precedence than +
• - has higher precedence than *
• + and - have same precedence
• + has higher precedence than *

Question 26

The number of tokens in the following C statement is printf("i=%d, &i=%x", i,&i);

• 13

• 6

• 10

• 9

Question 27

Which grammar rules violate the requirement of the operator grammar? A, B, C are variables and a, b, c are terminals

1) A → BC
2) A → CcBb
3) A → BaC
4) A → ε

• 1 only
• 1 and 2 only
• 1 and 3 only
• 1 and 4 only

Question 28

Which one of the following is a top-down parser?

• Recursive descent parser
• Shift left associative parser
• SLR(k) parser
• LR(k) parser

Question 29

Yacc stands for

• yet accept compiler constructs
• yet accept compiler compiler
• yet another compiler construct
• yet another compiler compiler

Question 30

Which statement is true?

• LALR parser is more powerful and costly as compare to other parsers

• All CFG\'s are LP and not all grammars are uniquely defined

• Every SLR grammar is unambiguous but not every unambiguous grammar is SLR

• LR(K) is the most general back tracking shift reduce parsing method