Calculate DAU/MAU ratio per user from products

Last updated: April 15, 2026

Quick Overview

Write SQL to compute DAU/MAU ratio grouped by user from products, handling nulls and duplicates.

Walmart

Data Manipulation (SQL/Python)

Data Scientist

Walmart

April 15, 2026

Data Scientist

Phone Screen

Data Manipulation (SQL/Python)

Medium

267

1,024 solved

Write SQL to compute DAU/MAU ratio grouped by user from products, handling nulls and duplicates.

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.

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Sample Answer

Problem Understanding

To solve the problem of calculating the Daily Active Users (DAU) and Monthly Active Users (MAU) ratio for Walmart from product interactions, we need to focus on user activity data. The relevant data w...

Approach

Select Data: Start by selecting the relevant columns from the 'user_activity' table, specifically user_id and activity_date.
Calculate DAU: Group the data by activity_date and coun...

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