Write a query to find average revenue from users
Last updated: October 25, 2025
Quick Overview
Write a SQL query to calculate average revenue from the users table, considering nulls and duplicates.
Datadog
October 25, 20256
8
3,436 solved
Write a SQL query to calculate average revenue from the users table, considering nulls and duplicates.
Data manipulation questions at Datadog test your ability to work with real-world datasets. This Onsite question evaluates your SQL proficiency, understanding of data modeling, and ability to derive insights from raw data.
What the Interviewer Expects
- Use advanced SQL features: window functions, CTEs, subqueries
- Write efficient queries that avoid common performance pitfalls
- Handle complex data transformations with multiple joins and aggregations
- Discuss indexing strategy and query optimization
- Address data quality issues: duplicates, missing values, outliers
Key Topics to Cover
How to Approach This
- Clarify the schema and expected output format before writing queries.
- Use CTEs (WITH clauses) to break complex queries into readable steps.
- Consider window functions (ROW_NUMBER, RANK, LAG, LEAD) for ranking and sequential analysis.
- Watch for NULLs, duplicates, and edge cases in JOINs and GROUP BY.
- For pandas, prefer vectorized operations over row-by-row iteration.
Possible Follow-up Questions
- How would you validate the correctness of your query results?
- How would you handle slowly changing dimensions in this scenario?
- What indexes would you create to support this query?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice SQL ProblemsSample Answer
Problem Understanding
To calculate the average revenue from the users table, we need to focus on the revenue column, which may contain NULL values and duplicates. The objective is to ensure that the average is calculated b...
Approach
- Select Unique Revenues: Use a DISTINCT clause to filter out duplicate revenue entries.
- Handle NULL Values: Use COALESCE to replace NULL revenues with 0 (or exclude them from the calcula...
Submit Your Answer
