Year-over-Year Product Growth | Dataford Interview Questions

Stryker's commercial analytics team wants to monitor annual sales performance for the Mako product line. Write a PostgreSQL query that calculates year-over-year sales growth from the available sales records.

Requirements

Join sales to products and include only products where product_line = 'Mako'.
Aggregate total sales by calendar year using sale_date and sales_amount.
Compare each year with the immediately preceding year and calculate growth as a percentage.
Return the years in ascending order. Return NULL for the first year when no prior-year sales exist.

Schema

products

Column	Type	Description
product_idPK	INTEGER	Unique product identifier
product_name	VARCHAR(100)	Name of the Stryker product
product_line	VARCHAR(50)	Stryker product line associated with the product

sales

Column	Type	Description
sale_idPK	INTEGER	Unique sale identifier
product_id	INTEGER	Product associated with the sale
sale_date	DATE	Date on which the sale was recorded
sales_amount	NUMERIC(12,2)	Sales value for the transaction

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