Database Interview Questions and Answers for Freshers

Database Interview Questions and Answers

 Here are some common interview questions and answers related to databases for freshers:

1. What is a database?

A database is a structured collection of data that is organized, stored, and managed to provide efficient retrieval and manipulation of information. It is a fundamental component of many software applications and serves as a repository for storing and accessing data.

Database Interview Questions

2. What are the different types of databases?

There are several types of databases, including relational databases, object-oriented databases, hierarchical databases, network databases, and NoSQL databases.

3. What is a relational database?

A relational database is a type of database that organizes data into tables with rows and columns. It establishes relationships between tables using keys, allowing efficient data retrieval and manipulation.

4. What is SQL?

SQL (Structured Query Language) is a programming language used to communicate with and manipulate relational databases. It is used for tasks such as querying data, updating data, and creating database structures.

5. What is normalization?

Normalization is the process of organizing data in a database to eliminate redundancy and improve data integrity. It involves breaking down tables into smaller, more specialized tables and establishing relationships between them.

6. What is a primary key?

A primary key is a unique identifier for a record in a database table. It ensures that each record can be uniquely identified and provides a way to enforce data integrity and establish relationships between tables.

7. What is a foreign key?

A foreign key is a field in a database table that refers to the primary key of another table. It establishes a relationship between the tables and enforces referential integrity.

8. What is indexing?

Indexing is a technique used to improve the performance of database queries by creating data structures that allow for quick data retrieval. Indexes are created on specific columns in a table to facilitate fast searching and sorting.

9. What is ACID in the context of databases?

ACID stands for Atomicity, Consistency, Isolation, and Durability. It is a set of properties that guarantee reliable processing of database transactions. Atomicity ensures that a transaction is treated as a single unit, Consistency ensures that data remains valid throughout the transaction, Isolation ensures that concurrent transactions do not interfere with each other, and Durability ensures that completed transactions are permanently saved.

10. What is the difference between a primary key and a unique key?

Both primary keys and unique keys are used to enforce uniqueness in a database table. However, a primary key is used to identify a record uniquely and cannot contain null values, while a unique key can allow null values and does not necessarily identify the record.

Remember, it's essential to understand the concepts and principles behind databases rather than just memorizing the answers. Use these questions and answers as a starting point to deepen your understanding and be prepared for a database-related interview.

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