30 Asked PostgreSQL Interview Questions and Answers (2024)

Ques 1. What is PostgreSQL, and how does it differ from other relational database systems?

PostgreSQL is an open-source relational database management system (RDBMS). It differs from others by its extensibility and support for SQL and procedural languages.

Ques 2. Explain the concept of ACID properties in the context of databases.

ACID stands for Atomicity, Consistency, Isolation, and Durability, ensuring the reliability of database transactions.

Ques 3. What is the purpose of the WHERE clause in a PostgreSQL query?

The WHERE clause filters records based on a specified condition, allowing selective data retrieval.

Ques 4. Describe the role of the PRIMARY KEY constraint in PostgreSQL.

The PRIMARY KEY constraint uniquely identifies each record in a table and ensures data integrity.

Ques 5. Explain the difference between INNER JOIN and LEFT JOIN in PostgreSQL.

INNER JOIN retrieves rows where there is a match in both tables, while LEFT JOIN retrieves all rows from the left table and matching rows from the right table.