SQL for Churn Trends | Dataford Interview Questions

Write a SQL query to identify customer churn trends across our subscription tiers over the last four quarters at Intuit.

For this exercise, use calendar quarters 2025 Q1 through 2025 Q4. Treat a customer as active at a quarter's start when the subscription began before that date and had not yet been canceled. Treat cancellations during the quarter as churn.

Output

One row per quarter and subscription tier.
Columns: quarter, tier_name, active_customers_start, churned_customers, and churn_rate.
Include tiers with no activity, use NULL for rates with no active customers, and order by quarter chronologically, then tier name alphabetically.

Schema

subscription_tiers

Column	Type	Description
tier_idPK	INT	Unique subscription tier identifier
tier_name	VARCHAR(100)	Intuit subscription tier name

subscriptions

Column	Type	Description
subscription_idPK	INT	Unique subscription identifier
customer_id	INT	Customer associated with the subscription
tier_id	INT	Subscription tier identifier
started_at	DATE	Subscription start date
canceled_at	DATE	Subscription cancellation date

Your question is SQL for Churn Trends. Start with the requirements and the two tables in the Question tab.

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Problem