Month-over-Month Sales Growth Query | Dataford Interview Questions

Write a query to calculate month-over-month growth in sales.

Use completed sales with non-null amounts. Return only months that have a preceding month in the data, and return NULL growth when the preceding month's sales are zero.

Output

One row per month, with month, current_sales, previous_sales, and growth_pct.
Include percentage growth rounded to two decimal places.
Sort chronologically by month.

Schema

sales

Column	Type	Description
sale_idPK	INT	Unique identifier for the sale
sale_date	DATE	Date on which the sale occurred
sale_amount	NUMERIC(12,2)	Sale amount in the reporting currency
status	VARCHAR(20)	Sales lifecycle status

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