DBMS Interview Questions and Answers in 2025 (100+ Q&A)

DBMS

Ques:- What restrictions can you apply when you are creating views?

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Right Answer:
When creating views, you can apply the following restrictions:

1. **No Indexes**: Views cannot have indexes directly.
2. **No Direct Updates**: Views based on multiple tables or with aggregate functions cannot be updated directly.
3. **Read-Only**: Some views are read-only and do not allow data modification.
4. **Security Restrictions**: Views can restrict access to specific columns or rows of the underlying tables.
5. **Complex Queries**: Views cannot include certain complex SQL features like ORDER BY or GROUP BY unless used with TOP or LIMIT.
6. **Schema Changes**: Changes to the underlying tables (like dropping columns) can invalidate the view.

DBMS

Ques:- Compare Non-clustered and clustered index

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Right Answer:
A clustered index determines the physical order of data in a table and can only be one per table, while a non-clustered index creates a separate structure from the data, allowing multiple non-clustered indexes per table. Clustered indexes are generally faster for range queries, while non-clustered indexes are better for lookups on non-key columns.

DBMS

Ques:- Define cursor.

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Right Answer:
A cursor is a database object used to retrieve, manipulate, and navigate through a result set row by row.

DBMS

Ques:- Who proposed the relational model?

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Right Answer:
Edgar F. Codd proposed the relational model.

DBMS

Ques:- What is Denormalization?

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Right Answer:
Denormalization is the process of intentionally introducing redundancy into a database by combining tables or adding duplicate data to improve read performance and simplify queries.

DBMS

Ques:- What is a degree of Relation?

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Right Answer:
The degree of a relation is the number of attributes (columns) in that relation (table).

DBMS

Ques:- What do you mean by transparent DBMS?

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Right Answer:
A transparent DBMS is a database management system that hides the complexities of the database from users, allowing them to interact with the database without needing to understand its underlying structure or operations.

DBMS

Ques:- When does checkpoint occur in DBMS?

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Right Answer:
A checkpoint occurs in a DBMS during the transaction processing to save the current state of the database, ensuring that all changes made by committed transactions are written to disk, and to minimize the amount of work needed for recovery in case of a failure.

DBMS

Ques:- What is a checkpoint in DBMS?

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Right Answer:
A checkpoint in DBMS is a process that saves the current state of the database to disk, ensuring that all changes made up to that point are recorded. This helps in recovering the database to a consistent state in case of a failure.

DBMS

Ques:- What is a view? How it is related to data independence?

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Right Answer:
A view is a virtual table in a database that is based on the result of a query. It does not store data itself but provides a way to present data from one or more tables. Views are related to data independence because they allow users to access data without needing to know the underlying table structures, enabling changes to the database schema without affecting how users interact with the data.

DBMS

Ques:- What is System R? What are its two major subsystems?

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Right Answer:
System R is a pioneering relational database management system developed at IBM. Its two major subsystems are the **Research Storage System (RSS)**, which handles data storage and retrieval, and the **Query Processing System (QPS)**, which is responsible for interpreting and executing SQL queries.

DBMS

Ques:- Define the “integrity rules”?

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Right Answer:
Integrity rules are constraints that ensure the accuracy and consistency of data in a database. The main types include:

1. **Entity Integrity**: Ensures that each table has a primary key and that the key is unique and not null.
2. **Referential Integrity**: Ensures that foreign keys correctly reference primary keys in related tables, maintaining valid relationships.
3. **Domain Integrity**: Ensures that all entries in a column fall within a defined set of valid values or data types.

DBMS

Ques:- Describe the three levels of data abstraction?

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Right Answer:
The three levels of data abstraction are:

1. **Physical Level**: This level describes how data is physically stored in the database, including the data structures and file formats.

2. **Logical Level**: This level defines what data is stored in the database and the relationships among those data. It focuses on the structure of the entire database.

3. **View Level**: This level provides a way for users to interact with the data. It defines how data is presented to users and what data they can access, often through different views or subsets of the data.

DBMS

Ques:- What are the disadvantage in File Processing System?

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Right Answer:
1. Data redundancy: Duplicate data can exist in multiple files, leading to inconsistency.
2. Difficulty in data access: Retrieving data can be complex and time-consuming.
3. Lack of data integrity: Ensuring accuracy and consistency of data is challenging.
4. Limited data sharing: Sharing data between applications is difficult.
5. Poor security: File systems often lack robust security measures.
6. Inflexibility: Changes to data structure require significant effort and can disrupt operations.
7. No support for concurrent access: Multiple users cannot easily access or modify data simultaneously.

DBMS

Ques:- What is Query evaluation engine?

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Right Answer:
A query evaluation engine is a component of a database management system that processes and executes database queries. It translates high-level queries into low-level operations, optimizes the execution plan, and retrieves the requested data efficiently.

DBMS

Ques:- What is DDL (Data Definition Language)?

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Right Answer:
DDL (Data Definition Language) is a subset of SQL used to define and manage all database objects, such as tables, indexes, and schemas. Common DDL commands include CREATE, ALTER, and DROP.

DBMS

Ques:- What is an Entity?

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Right Answer:
An entity is a distinct object or thing in a database that can be identified and has attributes. It represents a real-world object, such as a person, place, or event, that can be stored in a table.

DBMS

Ques:- What is E-R model?

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Right Answer:
The E-R model, or Entity-Relationship model, is a diagrammatic representation of the data structure in a database. It illustrates the entities (objects) in the system, their attributes, and the relationships between them.

DBMS

Ques:- What is Data Model?

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Right Answer:
A data model is a conceptual representation of how data is structured, organized, and related within a database. It defines the data elements, their relationships, and the rules for data manipulation and integrity.

DBMS

Ques:- What is the concept of sub-query in terms of SQL?

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Right Answer:
A sub-query is a query nested inside another SQL query, used to retrieve data that will be used in the main query. It can be placed in SELECT, INSERT, UPDATE, or DELETE statements and is typically enclosed in parentheses.

The DBMS (Database Management System) category on takluu.com is designed for students, IT professionals, and job seekers eager to master the fundamentals and advanced concepts of databases. In today’s data-driven world, understanding how databases work is critical for roles in software development, data analysis, and system administration.

This category covers core topics such as database models (relational, hierarchical, network), SQL queries, normalization, transactions, indexing, and database security. You’ll also learn about practical aspects like database design, backup and recovery, and performance optimization.

Interview questions often test your knowledge of how to efficiently manage large volumes of data, ensure data integrity, and implement secure database solutions. Knowing DBMS concepts helps you handle real-world challenges related to data storage and retrieval effectively.

At Takluu, we simplify complex DBMS topics with clear explanations, practical examples, and common interview questions. Whether you’re preparing for technical interviews or exams, this category equips you with the skills to confidently answer questions and solve problems related to databases.

Mastering DBMS opens doors to exciting career opportunities in software development, database administration, and data science. With our resources, you’ll be well-prepared to succeed and excel in the data-centric tech industry.

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