Write a query to find engagement score from users
Last updated: July 28, 2025
Quick Overview
Write a SQL query to calculate engagement score from the users table, considering nulls and duplicates.
PayPal
July 28, 20257
6
476 solved
Write a SQL query to calculate engagement score from the users table, considering nulls and duplicates.
Data manipulation questions at PayPal test your ability to work with real-world datasets. This Technical Screen 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
- What indexes would you create to support this query?
- How would you handle this if the data was spread across multiple databases?
- What would you do if this query needs to run every 5 minutes?
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Practice SQL ProblemsSample Answer
Problem Understanding
To calculate the engagement score from the users table, we need to identify relevant fields that contribute to this score. Typically, an engagement score can be derived from user activity metrics such...
Approach
- Identify Relevant Columns: Determine the metrics for engagement, such as login counts, transaction amounts, etc.
- Use CTEs: Create a Common Table Expression to aggregate user activities, ...
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