Most Common SQL Interview Questions for Analytics (2025)

Are you preparing for a data analyst or data science interview in 2025? SQL remains the #1 technical skill employers test for analytics roles. This comprehensive guide covers the most frequently asked SQL interview questions, real-world scenarios, and expert strategies to help you stand out and land your next job.

Why SQL Skills Matter in Analytics Interviews

SQL is the backbone of data analysis, powering everything from business dashboards to machine learning pipelines. Employers expect candidates to:

• Write efficient queries for large datasets
• Transform and clean data for analysis
• Optimize for performance and scalability
• Communicate logic and tradeoffs clearly

What Employers Typically Cover

According to industry experts, interviewers—from junior to senior level—expect candidates to have:

• A solid grasp of basic querying (WHERE, joins, aggregations)
• Fluency in advanced constructs (CTEs, window functions, subqueries)
• Experience with data transformations and conditional logic (CASE, string manipulation)
• Understanding of query optimization and performance tuning

[Source: datainterview.com, tryexponent.com]

Core SQL Interview Question Categories & Real Examples

1. Basics & Aggregation

• Find the second-highest salary from an Employees table.
• Count the number of active users in a given time period.
• Use aggregate functions (COUNT, SUM, AVG) and GROUP BY effectively.

2. Joins & Relationships

• Explain differences between INNER JOIN, LEFT JOIN, and others.
• Retrieve user details along with their latest activity using appropriate join logic.

3. Window Functions & CTEs

• Use ROW_NUMBER() to deduplicate data.
• Compute rolling averages (e.g., a 7-day moving average of sales).

4. Subqueries & CTEs

• Write queries that reference tables within subqueries.
• Simplify complex logic using WITH (CTE) structures.

5. Optimization & Performance (for Senior Roles)

• How do indexes help speed up queries?
• Why avoid full table scans, and how do they impact performance?

6. Analytics & Business Metrics

• Design a query to compute the average monthly rating per product given a reviews table.
• Calculate conversion rate by joining orders and sessions tables.

Real Interview Questions With Solutions

Problem A: Second Highest Salary

SELECT MAX(salary) FROM employees
WHERE salary < (SELECT MAX(salary) FROM employees);

Problem B: Monthly Average Ratings (Amazon-Inspired)

SELECT 
  EXTRACT(MONTH FROM submit_date) AS month,
  product_id,
  ROUND(AVG(stars), 2) AS avg_stars
FROM reviews
GROUP BY month, product_id
ORDER BY month, product_id;

Problem C: Rolling 7-Day Sales Average

SELECT 
  order_date,
  SUM(sales) AS daily_sales,
  AVG(SUM(sales)) OVER (ORDER BY order_date ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) AS rolling_7d_avg
FROM orders
GROUP BY order_date
ORDER BY order_date;

Tips to Ace Your SQL Interview

Frequently Asked Questions (FAQ)

Q: What are the most common SQL interview questions for analytics? A: Expect questions on joins, aggregations, window functions, subqueries, and business metrics (e.g., conversion rate, retention).

Q: How do I prepare for SQL interviews in 2025? A: Practice real-world problems, review query optimization, and be ready to explain your logic. Use mock interviews and online platforms.

Q: What SQL skills do employers value most? A: Efficient querying, data transformation, performance tuning, and clear communication of logic.

Q: How can I stand out in a SQL interview? A: Go beyond correct answers—optimize queries, explain tradeoffs, and relate solutions to business impact.

Next Steps & Further Resources

• Want more practice? Check out our guides on Data Analyst Salary and Data Scientist Salary.
• For advanced SQL, see Machine Learning Engineer Salary for real-world ML data pipeline examples.
• Ready to prep with feedback? → Try InterviewQs for free and practice with curated SQL rounds.

Optimized for 2025 interviews. Good luck on your analytics journey!