SQL Retention Rate Query | Dataford Interview Questions

Disney+ analytics needs to measure how many users from a January 2025 signup cohort returned to watch content during February 2025. Write a PostgreSQL query that calculates the cohort size, retained users, and retention rate.

Requirements

Define the cohort as users whose signup_date is from January 1 through January 31, 2025.
Define a retained user as a cohort user with at least one viewing session from February 1 through February 28, 2025.
Return one row containing the cohort size, retained user count, and retention rate as a percentage rounded to two decimal places.
Include cohort users with no qualifying February session in the denominator.

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
signup_date	DATE	Date the user registered
plan_name	VARCHAR(30)	Disney+ subscription plan
region	VARCHAR(30)	User's market region

viewing_sessions

Column	Type	Description
session_idPK	INT	Unique viewing session identifier
user_id	INT	User associated with the session
session_date	DATE	Date of the viewing session
device_type	VARCHAR(20)	Device used for viewing
minutes_watched	INT	Minutes watched during the session

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