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Customer Behavior Analysis in SQL

Introduction
Churned customers
Customer retention charts
Summary
10. Question 1

Instruction

Let's start with Question 1!

Exercise

Find the number of churned customers in weekly registration cohorts. Show the following columns: year, week, and churned_customers. Define churned customers as customers who haven't placed an order in the last 90 days. Order the results by year and week.

Don't show the rows for which the number of churned customers is 0.

Stuck? Here's a hint!