SQL Top 5 Stores by Sales Growth | Dataford Interview Questions

Sherwin-Williams operations leadership wants to identify stores with the strongest recent sales increases. Write a PostgreSQL query that compares each store's monthly completed sales with the preceding month.

Requirements

Aggregate non-null completed sales by store and calendar month.
Calculate the previous month's sales and percentage growth using a window function.
Exclude months without a prior month or with prior-month sales of zero.
Return the five highest growth store-month results, ordered by growth percentage descending, with deterministic tie-breaking.

Schema

stores

Column	Type	Description
store_idPK	INT	Unique Sherwin-Williams store identifier
store_name	VARCHAR(100)	Store display name
region	VARCHAR(50)	Operating region

store_sales

Column	Type	Description
sale_idPK	INT	Unique sales record identifier
store_id	INT	Store associated with the sale
sale_date	DATE	Date of the transaction
net_sales	DECIMAL(12,2)	Net sales amount
sale_status	VARCHAR(20)	Transaction processing status

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