Test: Relational Algebra, Tuple Calculus & SQL- 1

# Test: Relational Algebra, Tuple Calculus & SQL- 1

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## 10 Questions MCQ Test Question Bank for GATE Computer Science Engineering | Test: Relational Algebra, Tuple Calculus & SQL- 1

Test: Relational Algebra, Tuple Calculus & SQL- 1 for Computer Science Engineering (CSE) 2022 is part of Question Bank for GATE Computer Science Engineering preparation. The Test: Relational Algebra, Tuple Calculus & SQL- 1 questions and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus.The Test: Relational Algebra, Tuple Calculus & SQL- 1 MCQs are made for Computer Science Engineering (CSE) 2022 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Relational Algebra, Tuple Calculus & SQL- 1 below.
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Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 1

### The relational algebra expression equivalent to the following expression:  is:

Detailed Solution for Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 1

The expression

can be represented in relational algebra as

It says that select those rows from relation r where A = 10 union where B = 20.
Hence option (b) is correct.

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 2

### A relation (from the relational database model) consists of a set of tuples, which implies that

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 3

### Which of the following statements is correct with respect to entity integrity?

Detailed Solution for Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 3

According to entity integrity primary key of relation should not contain null values.

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 4

Which of the following operations is not part of the five basic set operations in relational algebra?

Detailed Solution for Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 4

Five primitive operators of Codd’s algebra are the selection, the projection the Cartesian product, the set union and the set difference.

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 5

Which of the following relational algebraic operation is not a commutative operation?

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 6

Consider a banking database with the following relation with three attributes loans (br_name, loan_no, amount).
Find the appropriate query for the given statements below:
“Find the loan number for each loan of an amount greater than 20000”

Detailed Solution for Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 6

Loans (br_name, loan_no, amount)
For the query “find the loan number for each loan of an amount greater than 20000”.
We have to check for each loan to find a loan number which is greater than 20,000.

Hence (b) is the correct option.

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 7

Let R(a, b, c) and S(d, e, f) be two relations in which d is the foreign key of S that refers to the primary key of R. Consider the following four operations R and S
1. Insert into R
2. Insert into S
3. Delete from R
4. Delete from S
Which of the following is true about the referential integrity constraint above?

Detailed Solution for Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 7

Referential integrity constraint: In relational model, two relation are related to each other over the basis of attributes, Every value of referencing attribute must be null or be available in the referenced attribute.

Here d is the foreign key of S that refers to the primary key of R.
1. Insert into R will not cause any violation.
2. Insert into S may cause violation because for each entry in ‘S ’ it must be. in ‘R ’ .
3. Delete from R may cause violation because for the deleted entry in R there may be referenced entry in the reIation S.
4. Delete from S will not cause any violation.
Hence (d) is the correct option.

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 8

Let r and s be two relations over the relation schemes R and S respectively, and let A be an attribute in R. Then the relational algebra expression   is always equal to

Detailed Solution for Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 8

The relational algebra expression:

Hence (c) is the required option.

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 9

Join Selectivity of a relation R in a natural join with a relation S is the _____

Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 10

Which of the following is wrong?

Detailed Solution for Test: Relational Algebra, Tuple Calculus & SQL- 1 - Question 10

is not equivalent because θ join is not cumulative hence the entries in   may not be same. Hence option (d) is correct.

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