Monthly Customers by Product and Booking Type | Dataford Interview Questions

Given a Bookings table, what is the total number of customers for each month, product and booking type?

Asked in the technical phone screen stage. Candidate was provided two tables, including a Bookings table, to perform data analysis. Write a SQL query using the provided tables.

Output

Return one row per month, product, and booking type.
Include month, product, booking_type, and total_customers.
Count each customer once within each combination, label missing product or booking type as Unknown, and order by month, product, and booking type.

Schema

bookings

Column	Type	Description
booking_idPK	INT	Unique booking identifier
customer_id	INT	Customer associated with the booking
booking_date	DATE	Date on which the booking was made
product_id	INT	Referenced product identifier
booking_type	VARCHAR(30)	Booking classification

products

Column	Type	Description
product_idPK	INT	Unique product identifier
product_name	VARCHAR(100)	Product name

Your question is Monthly Customers by Product and Booking Type. Start with the requirements and the two tables in the Question tab.

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Problem