DBMS MCQs with Answers and Explanations

Question #201

Which level of database architecture defines the entire logical structure of the database, including entities, relationships, and constraints, independent of physical storage?

A. Physical Level

B. Conceptual Level

C. View Level

D. Internal Level

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Correct Answer: Option B

Explanation:
The Conceptual (or Logical) level describes what data is stored in the entire database and what relationships exist among those data points.

This question belongs to: Computer Database Management System (DBMS)

Question #202

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The ability to modify the physical schema without forcing application programs to be rewritten is called what?

A. Structural Integrity

B. Logical Data Independence

C. Physical Data Independence

D. Data Redundancy

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Correct Answer: Option C

Explanation:
Physical Data Independence is the ability to modify the physical schema (like storage devices or file structures) without changing the conceptual or external schemas.

This question belongs to: Computer Database Management System (DBMS)

Question #203

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Which of the following terms refers to the duplication of data across multiple locations in a non-DBMS file system?

A. Data Integrity

B. Data Security

C. Data Isolation

D. Data Redundancy

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Correct Answer: Option D

Explanation:
Data Redundancy refers to the unnecessary duplication of the exact same data in multiple files or locations, which wastes storage and can cause inconsistencies.

This question belongs to: Computer Database Management System (DBMS)

Question #204

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When the same data is updated in one location but remains unchanged in another location, it creates a state of what?

A. Data Inconsistency

B. Data Integrity

C. Data Security

D. Data Independence

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Correct Answer: Option A

Explanation:
Data Inconsistency occurs when different versions of the same data appear in different places due to uncontrolled data redundancy.

This question belongs to: Computer Database Management System (DBMS)

Question #205

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Who proposed the relational database model based on mathematical relation theory in 1970?

A. Charles Bachman

B. E.F. Codd

C. Dennis Ritchie

D. James Gosling

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Correct Answer: Option B

Explanation:
Dr. Edgar Frank Codd (E.F. Codd) invented the relational model for database management while working for IBM in 1970.

This question belongs to: Computer Database Management System (DBMS)

Question #206

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How many fundamental rules did E.F. Codd define to determine whether a database system qualifies as a true relational database management system?

A. 14 rules

B. 8 rules

C. 10 rules

D. 12 rules

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Correct Answer: Option D

Explanation:
E.F. Codd formulated 12 rules (numbered 0 to 11, often called Codd's 12 Rules) to evaluate relational database management systems.

This question belongs to: Computer Database Management System (DBMS)

Question #207

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The range of all permissible and valid values that an attribute can hold is formally defined as its what?

A. Relation

B. Domain

C. Schema

D. Tuple

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Correct Answer: Option B

Explanation:
A Domain is the pool of legal, atomic values from which an attribute can take its value.

This question belongs to: Computer Database Management System (DBMS)

Question #208

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Which of the following database models organizes data in a tree-like upside-down structure with parent-child relationships?

A. Network Model

B. Hierarchical Model

C. Object-Oriented Model

D. Relational Model

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Correct Answer: Option B

Explanation:
The Hierarchical Model stores data in a tree-like configuration where each child node has exactly one parent node.

This question belongs to: Computer Database Management System (DBMS)

Question #209

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Which database model improves upon the hierarchical model by allowing a child record to have multiple parent records, creating a graph-like structure?

A. Star Schema

B. Network Model

C. Relational Model

D. Flat File Model

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Correct Answer: Option B

Explanation:
The Network Model represents data as graphs where a record (node) can have multiple parent and child records, solving the strict single-parent limitation of hierarchical systems.

This question belongs to: Computer Database Management System (DBMS)

Question #210

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In an Entity-Relationship (ER) diagram, what geometric shape is used to represent an entity type?

A. Diamond

B. Ellipse

C. Triangle

D. Rectangle

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Correct Answer: Option D

Explanation:
In standard ER modeling notation, rectangles are used to represent entity sets or entity types.

This question belongs to: Computer Database Management System (DBMS)

Question #211

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What geometric symbol is used in an Entity-Relationship (ER) diagram to represent a relationship between entities?

A. Oval

B. Rectangle

C. Diamond

D. Circle

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Correct Answer: Option C

Explanation:
Diamonds are utilized in ER diagrams to depict relationships between two or more entities.

This question belongs to: Computer Database Management System (DBMS)

Question #212

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In an Entity-Relationship (ER) diagram, attributes are represented using which shape?

A. Diamond

B. Ellipse/Oval

C. Rectangle

D. Square

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Correct Answer: Option B

Explanation:
Ellipses or ovals are used to represent attributes (properties) of entities in ER diagrams.

This question belongs to: Computer Database Management System (DBMS)

Question #213

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An attribute that can be broken down into smaller, independent sub-parts with independent meanings (such as Name into First_Name and Last_Name) is called a what?

A. Derived Attribute

B. Multi-valued Attribute

C. Simple Attribute

D. Composite Attribute

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Correct Answer: Option D

Explanation:
A Composite Attribute is one that can be divided into smaller sub-components or meaningful independent fields.

This question belongs to: Computer Database Management System (DBMS)

Question #214

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What is an attribute called when it can hold more than one value for a single entity instance, such as multiple phone numbers for a person?

A. Derived Attribute

B. Complex Attribute

C. Multi-valued Attribute

D. Composite Attribute

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Correct Answer: Option C

Explanation:
A Multi-valued Attribute is an attribute that can store multiple distinct values for a single entity instance (e.g., skill_set, phone_numbers).

This question belongs to: Computer Database Management System (DBMS)

Question #215

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An attribute whose value is computed dynamically from another attribute (such as calculating Age from Date_of_Birth) is called a what?

A. Multi-valued Attribute

B. Base Attribute

C. Stored Attribute

D. Derived Attribute

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Correct Answer: Option D

Explanation:
A Derived Attribute is an attribute whose values are not stored physically in the database but are calculated at runtime from other stored attributes.

This question belongs to: Computer Database Management System (DBMS)

Question #216

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What type of entity cannot be uniquely identified by its own attributes alone and must rely on a relationship with a parent entity?

A. Strong Entity

B. Associative Entity

C. Abstract Entity

D. Weak Entity

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Correct Answer: Option D

Explanation:
A Weak Entity is an entity that does not possess its own primary key and depends on an identifying relationship with a strong (owner) entity.

This question belongs to: Computer Database Management System (DBMS)

Question #217

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Which language category in SQL is used by database administrators to grant and revoke access privileges and security permissions?

A. DML

B. DDL

C. TCL

D. DCL

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Correct Answer: Option D

Explanation:
Data Control Language (DCL) includes commands like GRANT and REVOKE, which manage privileges and security configurations for database users.

This question belongs to: Computer Database Management System (DBMS)

Question #218

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Which of the following commands is a part of Transaction Control Language (TCL) in SQL?

A. GRANT

B. DELETE

C. COMMIT

D. ALTER

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Correct Answer: Option C

Explanation:
COMMIT is a TCL command used to permanently save all modifications made during the current transaction into the database.

This question belongs to: Computer Database Management System (DBMS)

Question #219

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Which SQL command is used to reverse or undo all modifications made during the current transaction that have not yet been committed?

A. REVERT

B. UNDO

C. ROLLBACK

D. SAVEPOINT

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Correct Answer: Option C

Explanation:
The ROLLBACK command is a TCL statement used to undo transactions, restoring the database to its last committed or safe state.

This question belongs to: Computer Database Management System (DBMS)

Question #220

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Which clause is used in a SQL SELECT statement to organize matching rows into summary groups based on one or more columns?

A. HAVING

B. GROUP BY

C. SORT BY

D. ORDER BY

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Correct Answer: Option B

Explanation:
The GROUP BY clause groups rows that have the same values into summary rows, often used alongside aggregate functions like COUNT(), MAX(), or AVG().

This question belongs to: Computer Database Management System (DBMS)

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