Query Guest Retention by Channel | Dataford Interview Questions

Marriott International wants to monitor whether guests who completed a booking return in the following month. Write a PostgreSQL query that calculates monthly guest retention by the guest's booking channel in the cohort month.

Requirements

Consider only bookings with booking_status = 'Completed'.
Treat each guest as one monthly booking-channel cohort member, even if the guest has multiple bookings in that month.
For each cohort month and booking channel, calculate the number of prior-month guests, the number who completed another booking in the next month, and the retention rate as a percentage.
Replace a missing booking channel with Unknown, and sort by retention month and booking channel.

A retained guest may return through any booking channel. The segment represents the channel used in the cohort month.

Schema

guests

Column	Type	Description
guest_idPK	INT	Unique guest identifier
guest_name	VARCHAR(100)	Guest full name
loyalty_tier	VARCHAR(30)	Marriott Bonvoy loyalty tier

bookings

Column	Type	Description
booking_idPK	INT	Unique booking identifier
guest_id	INT	Guest who made the booking
booked_at	TIMESTAMP	Timestamp when the booking was made
booking_channel	VARCHAR(40)	Booking source
booking_status	VARCHAR(20)	Booking lifecycle status

Your question is Query Guest Retention by Channel. Start with the requirements and the two tables in the Question tab.

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