DBMS MCQ Quiz - Objective Question with Answer for DBMS - Download Free PDF

The correct answer is Volume, Variety, Velocity.

Key Points

•  Big data refers to large and complex data sets that cannot be easily processed or managed using traditional data processing tools or database management systems.
• It often involves large amounts of unstructured or semi-structured data, such as text, images, and video, that require advanced analytical techniques to extract meaningful insights.
• The three V's of big data are:
• Volume: The amount of data being generated is enormous and constantly growing. This can range from terabytes to petabytes of data.
• Velocity: The speed at which data is being generated, processed, and analyzed is increasing. Real-time data streams are becoming more common, and the need for fast data processing and analysis is essential.
• Variety: Data comes in many different formats, including structured, semi-structured, and unstructured data. This includes data from traditional sources such as databases and spreadsheets, as well as data from social media, weblogs, sensors, and other sources.

Hence, the correct answer is Volume, Variety, Velocity

Correct answer is Option1

Explanation:Use the union rule to replace

EF → G and EF → H 

EF → GH

F = { A → B  ABCD → E  EF → GH  ACDF → EG }

B is extraneous in ABCD → E because B ∈ ABCD and {A → B, ABCD → E, EF → GH, ACDF → EG}

logically implies {A → B, ACD → E, EF → GH, ACDF → EG}.

This is because every  ACD → E.

This FD can be derived using Armstrong’s Axioms from A → B and ABCD → E via transitivity rule

So remove B from ABCD → E.

F = { A → B ACD → E  EF → GH ACDF → EG }

E is extraneous in ACDF → EG because E ∈ EG and {A → B, ACD → E, EF → GH, ACDF → G}

logically implies {A → B, ACD → E, EF → GH, ACDF → EG}

remove E from ACDF → EG

F = { A → B ACD → E EF → GH ACDF → G}

G is extraneous in ACDF → G. Note that ACDF → G is already implied by ACD → E and EF → GH in F

remove ACDF → G from F.

None of the remaining FD's in F have extraneous attributes so the minimal cover is

A → B, ACD → E, EF → G, EF → H.

Hence the correct answer is option 1. 

The correct answer is option 4.

Object Oriented DBMS:

Object-oriented DBMS is based on the object-oriented programming paradigm's model. They are useful for expressing both consistent data saved in databases and transitory data encountered in running applications. They employ simple, reusable parts known as objects.

Explanation:

Object-oriented databases closely relate to object-oriented programming concepts. The four main ideas of object-oriented programming are:

• Polymorphism
• Inheritance
• Encapsulation
• Abstraction

These four attributes describe the critical characteristics of object-oriented management systems.

Hence the correct answer is ​OODBMS.

Additional InformationNetwork DBMS:

Network DBMS is one where the relationships among data in the database are of type many to many in the form of a network.

Relational DBMS:

In relational databases, the database is represented in the form of relations. Each relation models an entity and is represented as a table of values. In the relation or table, a row is called a tuple and denotes a single record.

Distributed DBMS:

A distributed database is a set of interconnected databases that are distributed over the computer network or internet.

The correct option is (2)

Candidate key

Concept:-

The candidate key can be called a super key, as each candidate key is a subset of the super key. The super key with all necessary attributes is known as the candidate key. The super key with unnecessary attributes cannot be considered a candidate key.

Key Points

• A Candidate key is a minimal super key, meaning that it would cease to be a super key if you removed any attribute from the set.
• A minimum super key is referred to as a candidate and the main key since the primary key is chosen from the candidate keys.
• The minimal set of attributes that can uniquely identify a tuple is known as candidate key. For example, STUD_NO in STUDENT relation. It is a minimal super key.

Additional InformationForeign keys:- The characteristic that establishes the relationship between tables is the foreign key of a table. A foreign key is a column or columns of data in one table that connects to the primary key data in the original table.

Primary key:- The very minimum set of characteristics necessary to identify each row in a database is known as the primary key. It is chosen from a list of potential keys. The primary key might be any candidate's key.

Reference key:- The primary key that is used as a reference in the other table is known as the Reference key.

The correct answer is (I) and (II) are true

Concept:

Statement 1: A super key is an attribute or combination of attributes that uniquely identify records in an RDBMS table.

True, A super key, or just key, is a combination of every attribute that may be used to specifically identify rows (or tuples) in a database. This indicates that a superkey may contain additional information that isn't required for uniquely identifying table rows.

Statement 2: A candidate key is a subset of a super key.

True, A Candidate key is a subset of Super keys and is clear of any unnecessary attributes that are not essential for tuple identification. For all tuples, the Candidate key value is distinct and non-null. Additionally, each table must include at least one Candidate key.

Statement 3: All super keys are candidate keys but vice versa is not true.

False, Candidate keys are a subset of Super keys. They contain only those attributes which are required to uniquely identify tuples. All Candidate keys are Super keys. But the vice-versa is not true.

Hence the correct answer is (I) and (II) are true.

The correct answer is constraint-based languages.

Key Points

Programming languages are classified in variety of ways and generation is one of them.

• Generation are further classified as: First-generation, second-generation, third-generation, fourth-generation, fifth-generation.
• Fifth generation language is applied to logic and constraint-based languages like Prolog.

Additional Information

• Assembly languages → Second-generation
• Machine languages → First-generation
• High Level language → Third-generation

Rules for finding a minimum number of tables required for an ER diagram:

1) A strong entity with single or composite attributes requires one table.

2) A strong entity with multivalued attributes requires two tables.

3) In the case of many to many relations between two entities, 3 tables are required.

Explanation:

There is one to many relationships between R₁and R₂. So, two tables are required for two entities. But, entity R₁ contains multivalued attribute B, due to which one table for this is also needed.

Here we have 1 to Many relation so we requires two tables.

Attribute B being multi-valued, we need to remove the multi-valued attribute B to convert the given entity-relationship diagram into a relational database.

As relational database do not allow multi-valued attributes. We have to introduce a new table.

So, the number of tables is as below:
R1
R12R2
A table for B (Multi-valued attribute)
So, a total of 3 tables are required for the given entity relational diagram.

So, option 3 is the correct answer.

Concept:

The closure of F, denoted as F+, is the set of all regular FD, that can be derived from.

For trivial functional dependency,

Let A and be two sets consists of attributes of a relation

A → B

A  B 

Explanation:

Option 1: 

{P, R} → {S, T}

{P, R}  {S, T}

Not a trivial functional dependency

Option 2: 

{P, R} → {R, T}

{P, R}  {R, T}

Not a trivial functional dependency

Option 3: 

{P, S} → {S}

{P, S}  {S}

It is a trivial functional dependency

Option 4: 

{P, S, U} → {Q}

{P, S, U}  {Q}

Not a trivial functional dependency

NOTE:

 → superset

 → not superset

Concept:

An attribute that can be derived from other attributes of the entity type is known as a derived attribute, derived attribute is represented by a dashed eclipse.

Explanation:

In the ER model,

Option 1: Double ellipse

Multivalued attribute

Option 2: Dashed ellipse

Derived attribute

Option 4: Ellipse with attribute name underlined

Key attribute

Concept:

Total participation: It specifies that each entity in the entity set must compulsorily participate in at least one relationship instance in that relationship set.

Partial participation: It specifies that each entity in the entity set may or may not participate in the relationship instance in that relationship set.

Explanation:

In one to many or many to one relation, the relation between two entities is merged on the many side with total participation. As, it is given that relationship R doesn’t have its own attributes. So, it must be combined with entity A. So, the relation must be many to one and there should be total participation of A in R.

Answer: Option 3

Concept: 

Foreign Key :is the set of attributes in a particular relation whose values are belongs to primary key of same relation or other relation.

Explanation: 

Statement 1: A relation scheme can have at most one foreign key.

There is no such restriction on how many number of Foreign keys a particular relation can have. A relation can have as many number of Foreign keys as Required. 

So this statement is false.

Statement 2: foreign key in a relation scheme R cannot be used to refer to tuples of R.

There is no such constraint. Foreign key can be used to refer to primary key of the same relation. Self-referencing relations are examples of such foreign key. So this statement is also false.

So option 3 is the correct answer.

Function Dependencies:

{(E, F} → {G}, {F} → {I, J}, {E, H} → {K, L}, {K} → {M}, {L} → {N}}

Option 1: {E, F}

{E, F}⁺ = {E, F, G, I, J}

Since K, L, M and N is missing in RHS ∴ it is not a key

Also, {E} cannot be a key because {E} is subset of {E, F}

Option 2: {E, F, H}

{E, F, H}⁺ = {E, F, H, G, I, J, K, L, M, N}

∴ it is a key

Key for R is {E, F, H}.

Important Points:

In relation algebra, key is primary key or candidate key.

{E, F, H, K, L} is super key. 

The correct option is (4)

All options are correct

Key Points

• By decreasing isolated files in which the same data is repeated, a DBMS can reduce data redundancy and inconsistency.
• Although the DBMS may not be able to completely eliminate data redundancy, it can help limit it.
• The overall quality, completeness, and consistency of data is known as data integrity. Data integrity also refers to the data's safety and security in terms of regulatory compliance, such as GDPR compliance.
• Data integrity is critical because it ensures and safeguards your data's searchability and traceability back to its original source.
• A relational database is a collection of data elements that are linked by predetermined connections. These elements are laid out in a table format with columns and rows.
• Relationships enable relational databases to partition and store data in several tables while also linking disparate data pieces.
• The database management system (DBMS) organizes and manages incoming data, as well as allows users and other programs to modify or extract it.

The correct answer is "option 3".

EXPLANATION:

On converting the given ER diagram into the relational table, we will get three tables -

Hence, Exam (ExamID, NID, ExamName) is not a possible relation.

• Directory-based cache coherence is a type of cache coherence mechanism, where directories are used to manage caches in place of snoopy methods due to their scalability.
• For a multi-processor architecture,  in the directory-based protocol, a write transaction is forwarded to only those processors that are known to possess a copy of newly altered cache line
• It can be used to target both the performance and scalability of directory systems.

Additional Information

• Bus snooping methods scale poorly due to the use of broadcasting.