Nptel Introduction to Database Systems Week 3 Assignment Answer

ABOUT THE COURSE :

Databases are the backbone of almost all the digital services and e-governance solutions. Modern businesses and financial systems heavily depend on databases systems and transaction processing for their successful operation. This course introduces the students to the various theoretical and practical principles involved in the design and use of databases systems with the help of database management systems (DBMS) and the SQL Standard

INTENDED AUDIENCE : Any Interested Learners

PREREQUISITES : Studying B Tech (computer science) 3rd year, Discrete Mathematics or Discrete Structures, Programming and Data Structures

Nptel Introduction to Database Systems Week 3 Assignment Answer

Course layout

Week 1 : Introduction and part of E/R Model Module
Week 2 : ER Model Module
Week 3 : Relational Model Module
Week 4 : Relational Model Module
Week 5 : TRC Module and part of SQL Module
Week 6 : SQL Module
Week 7 : Indexes Module
Week 8 : Indexes Module + Query Processing Module
Week 9 : Normal Forms Module
Week 10 : Normal Forms Module
Week 11 : Transaction Processing Module
Week 12 : Transaction Processing Module

Nptel Introduction to Database Systems Week 3 Assignment Answer

Week 3 : Assignment 3

Due date: 2025-02-12, 23:59 IST.

Assignment not submitted

1 point

Which of the following statements is TRUE?

A key for a relation can be figured out just by looking at the instance data.

A relation has exactly one key.

It is possible that a relation has no key.

A key for a relation can only be determined from the meaning of its attributes.

State if the following statements are TRUE or FALSE:

1 point

In an instance of a relation, it is possible that the value of a key attribute is NULL in a certain row.

True

False

1 point

It is possible for a foreign key of a relation to refer to the primary key of the relation itself.

True

False

1 point

Every relation scheme can have at most one foreign key

True

False

1 point

If K is supposed to be a key for scheme R, any relation instance r on R should not have two tuples that have identical values for attributes in K.

True

False

1 point

Consider the following tables:

How many tuples exist in the query $(A \cup B) ⟗_{(A . i d > 20 \lor C . i d < 10)} C ?$

1 point

Consider the following relations $A (X, Y, Z)$ and $B (D, E, F)$ :

What is the result of the following expression: $Π_{(X, Y)} (σ_{(X = 1) \lor (X = 4)} (A)) - Π_{(D, E)} (σ_{(D \neq 3)} (B))$

{(6,8), (9,9)}

Empty relation

A relation with scheme $(X, Y)$ and tuples { (6,8) }

A relation with scheme $(X, Y)$ and tuples { (9,9) }

1 point

Consider the following relations A(X,Y,Z) and B (D,E,F) and find out how many tuples will there be in the result of the following relational algebra expression?

$A ⨝_{(A . X >= B . D \lor A . Z < = B . F)} B$

1 point

Information about a collection of students is given by the relation studInfo(studId, name, sex, yearOfJoin). The relation enroll(studId, courseId) gives which student has enrolled for (or taken) that course(s). Assume that every course is taken by at least one male and at least one female student. What does the following relational algebra expression represent?

$Π_{c o u r s e I d} ((Π_{s t u d I d} (σ_{s e x =" F e m a l e "} (s t u d I n f o)) ⨯ Π_{c o u r s e I d} (e n r o l l)) - e n r o l l)$

Courses in which all female students have enrolled.

Courses in which a proper subset of female students have enrolled.

Courses in which all male students have enrolled.

Courses in which only female students have enrolled.

1 point

Choose the correct statement(s):

Two schemes are union compatible if the domain of at least one pair of corresponding attributes match.

A join operation is equivalent to performing a cross product of its operands followed by a select operation using the join condition.

The operators ${σ, π, \times, ⋃, -}$ constitute a complete set of relational algebra operators.

The difference relational algebra operator requires its operands to be union-compatible.

1 point

Consider the following relations A(X,Y,Z) and B(X,Y) and the given instances. What is the result of the relational algebra expression?
$A \div B$

Empty relation

A relation with scheme Z and tuple { (3) }

A relation with scheme Z and tuples { (3), (5) }

{3,5}

1 point

Given two union compatible relations X(A,B) and Y(C,D). What is the result of the operation?

$X ⋈_{(A = C) \land (B = D)} Y$

$X \cup Y$

$X \cap Y$

$X - Y$

$X \div Y$

1 point

If X, Y and Z are as specified below, which of the following statements is TRUE wrt different keys of a relational DB?

X = set of all primary keys
Y = set of all candidate keys
Z = set of all super keys

$X \subseteq Z \subseteq Y$

$Z \subseteq X \subseteq Y$

$X \subseteq Y \subseteq Z$

$Y \subseteq X \subseteq Z$

Nptel Introduction to Database Systems Week 3 Assignment Answer

Nptel Introduction to Database Systems Week 3 Assignment Answer

Course layout

Nptel Introduction to Database Systems Week 3 Assignment Answer

Week 3 : Assignment 3

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