SQL Interview Questions

Introduction

A curated, reusable bank of SQL interview questions covering fundamentals to advanced — exactly what FAANG, fintech and SaaS hiring managers ask.

Understanding the topic

Core concepts to understand:

• Fundamentals: SELECT/WHERE/GROUP BY/JOIN.
• Indexes & performance.
• Transactions & isolation.
• Schema design.
• Window functions & CTEs.

Syntax reference

Visual workflow / architecture:

Interview SQL ladder
Junior  → SELECTs, JOINs, GROUP BY
Mid     → indexes, transactions, design
Senior  → optimization, distributed, governance

Real-world use

Used in interviews at Google, Stripe, Shopify, Uber, Airbnb, Booking — any company that takes data seriously.

Best practices

• Write SQL out loud.
• Always discuss trade-offs.
• Ask clarifying questions about schema and scale.

Hands-on exercise

Interview preparation — practice these questions:

• Q1. What is SQL?
• Q2. Difference between SQL and NoSQL?
• Q3. What is a primary key?
• Q4. Explain INNER JOIN and LEFT JOIN.
• Q5. What are indexes in SQL?
• Q6. What is normalization?
• Q7. Explain ACID properties.
• Q8. How do you optimize slow SQL queries?