Write a query to find DAU/MAU ratio from products
Last updated: January 10, 2026
Quick Overview
Write a SQL query to calculate DAU/MAU ratio from the products table, considering nulls and duplicates.
Neon
January 10, 2026119
4
1,820 solved
Write a SQL query to calculate DAU/MAU ratio from the products table, considering nulls and duplicates.
Data manipulation questions at Neon test your ability to work with real-world datasets. This Phone Screen question evaluates your SQL proficiency, understanding of data modeling, and ability to derive insights from raw data.
What the Interviewer Expects
- Write syntactically correct SQL with proper JOIN and WHERE clauses
- Use GROUP BY and aggregate functions appropriately
- Handle NULL values correctly in your queries
- Explain the query execution plan at a high level
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 optimize this query for a table with 100 million rows?
- How would you validate the correctness of your query results?
- What indexes would you create to support this query?
- How would you handle slowly changing dimensions in this scenario?
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Approach
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Solution Pattern
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