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

DBMS

Ques:- What is 4NF?

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Right Answer:
Fourth Normal Form (4NF) is a level of database normalization that eliminates multi-valued dependencies. A table is in 4NF if it is in Boyce-Codd Normal Form (BCNF) and has no non-trivial multi-valued dependencies, meaning that no attribute in the table is dependent on another attribute in a way that allows multiple values for that attribute.

DBMS

Ques:- What is 3NF?

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Right Answer:
3NF, or Third Normal Form, is a database normalization level where a table is in 2NF and all its attributes are functionally dependent only on the primary key, eliminating transitive dependencies.

DBMS

Ques:- What is 2NF?

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Right Answer:
2NF, or Second Normal Form, is a database normalization level where a table is in First Normal Form (1NF) and all non-key attributes are fully functionally dependent on the primary key. This means that no non-key attribute should depend on only a part of a composite primary key.

DBMS

Ques:- What is BCNF (Boyce-Codd Normal Form)?

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Right Answer:
BCNF (Boyce-Codd Normal Form) is a type of database normalization that is a stronger version of the Third Normal Form (3NF). A table is in BCNF if, for every one of its non-trivial functional dependencies (X → Y), X is a superkey. This means that every determinant in the table must be a candidate key, ensuring that there are no redundancy and anomalies in the data.

DBMS

Ques:- What is 1 NF (Normal Form)?

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Right Answer:
1 NF (First Normal Form) requires that a database table has a primary key and that all its columns contain atomic (indivisible) values, with each entry in a column being of the same data type and each column containing unique information. Additionally, there should be no repeating groups or arrays in any row.

DBMS

Ques:- What is Union, minus and Interact commands?

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Right Answer:
The UNION command combines the results of two or more SELECT queries, removing duplicates. The MINUS command returns rows from the first SELECT query that are not present in the second SELECT query. The INTERSECT command returns only the rows that are common to both SELECT queries.

DBMS

Ques:- Difference between delete and truncate?

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Right Answer:
DELETE removes rows from a table based on a condition and can be rolled back, while TRUNCATE removes all rows from a table without conditions and cannot be rolled back. TRUNCATE is generally faster and does not log individual row deletions.

DBMS

Ques:- What are the types of constraint?

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Right Answer:
The types of constraints in a database are:

1. **Primary Key Constraint** - Uniquely identifies each record in a table.
2. **Foreign Key Constraint** - Ensures referential integrity between two tables.
3. **Unique Constraint** - Ensures all values in a column are unique.
4. **Not Null Constraint** - Ensures a column cannot have a NULL value.
5. **Check Constraint** - Ensures that all values in a column satisfy a specific condition.
6. **Default Constraint** - Provides a default value for a column when no value is specified.

DBMS

Ques:- Why is a database considered to be ‘self-describing’?

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Right Answer:

A database is considered 'self-describing' because it contains not only the data itself but also metadata, which is information about the structure, relationships, and constraints of the data. This allows the database to define its own schema and understand how to interpret the stored data.

DBMS

Ques:- What are data and information, and how are they related in a database?

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Right Answer:
Data refers to raw facts and figures that can be processed, while information is the processed and organized data that is meaningful and useful. In a database, data is stored in tables, and when it is queried and analyzed, it becomes information that can be used for decision-making.

DBMS

Ques:- Can you explain insert ,update and delete query ?

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Right Answer:
**Insert Query:** Used to add new records to a table.
Example: `INSERT INTO table_name (column1, column2) VALUES (value1, value2);`

**Update Query:** Used to modify existing records in a table.
Example: `UPDATE table_name SET column1 = value1 WHERE condition;`

**Delete Query:** Used to remove records from a table.
Example: `DELETE FROM table_name WHERE condition;`

DBMS

Ques:- State difference between simple file and database ?

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Right Answer:
A simple file stores data in a flat format without structure, while a database organizes data in a structured way using tables, allowing for efficient querying, relationships, and data management.

DBMS

Ques:- Explain in brief the different normalization forms?

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Right Answer:
1. **First Normal Form (1NF)**: Ensures that all columns contain atomic values, and each entry in a column is of the same data type. There are no repeating groups or arrays.

2. **Second Normal Form (2NF)**: Achieved when a table is in 1NF and all non-key attributes are fully functionally dependent on the primary key, eliminating partial dependencies.

3. **Third Normal Form (3NF)**: A table is in 2NF and all the attributes are functionally dependent only on the primary key, removing transitive dependencies.

4. **Boyce-Codd Normal Form (BCNF)**: A stronger version of 3NF where every determinant is a candidate key, addressing certain anomalies not handled by 3NF.

5. **Fourth Normal Form (4NF)**: A table is in BCNF and has no multi-valued dependencies, ensuring that no attribute is dependent on another non-key attribute.

6. **Fifth Normal

DBMS

Ques:- How is ACID property related to Database ?

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Right Answer:
ACID properties in a database ensure that transactions are processed reliably. ACID stands for Atomicity (transactions are all-or-nothing), Consistency (transactions bring the database from one valid state to another), Isolation (transactions do not interfere with each other), and Durability (once a transaction is committed, it remains so even in case of a system failure).

DBMS

Ques:- What is weak entity ?

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Right Answer:
A weak entity is an entity that cannot be uniquely identified by its own attributes alone and relies on a "strong" or "owner" entity for its identification. It typically has a partial key and is dependent on the strong entity for its existence.

DBMS

Ques:- What Is Lossless Join Property?

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Right Answer:
The Lossless Join Property ensures that when a database is decomposed into smaller tables, the original table can be perfectly reconstructed by joining these smaller tables without any loss of data.

DBMS

Ques:- How Does Tuple-oriented Relational Calculus Differ From Domain-oriented Relational Calculus?

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Right Answer:
Tuple-oriented relational calculus focuses on tuples as whole records, using variables that represent entire tuples from a relation. In contrast, domain-oriented relational calculus focuses on individual attributes or fields, using variables that represent single values from the domains of those attributes.

DBMS

Ques:- What Is Sdl (storage Definition Language)?

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Right Answer:
SDL (Storage Definition Language) is a subset of SQL used to define the structure of a database, including the creation and modification of database objects such as tables, indexes, and schemas.

DBMS

Ques:- What Is Vdl (view Definition Language)?

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Right Answer:
VDL (View Definition Language) is a type of language used to define views in a database. It allows users to create, modify, and manage the structure of views, which are virtual tables representing the result of a query on one or more tables.

DBMS

Ques:- What is Data Warehousing.

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Right Answer:
Data warehousing is the process of collecting, storing, and managing large volumes of data from different sources in a central repository, designed for analysis and reporting to support decision-making.

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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