Top 5 Instruments by Region | Dataford Interview Questions

Write a SQL query to identify the top 5 selling medical instruments by region over the last three quarters.

Use the provided sales, instrument, and region data. Treat the latest quarter represented in the data as the ending quarter. Rank instruments within each region by total units sold, with instrument name ascending as the tie-breaker.

Output

One row per qualifying region and instrument.
Columns: region_name, instrument_name, units_sold, and sales_rank.
Include at most five instruments per region, ordered by region name and rank.

Schema

instrument_sales

Column	Type	Description
sale_idPK	INT	Unique sales transaction identifier
instrument_id	INT	Instrument sold
region_id	INT	Sales region
sale_date	DATE	Date of the sale
units_sold	INT	Number of instruments sold

instruments

Column	Type	Description
instrument_idPK	INT	Unique instrument identifier
instrument_name	VARCHAR(150)	Medical instrument name

regions

Column	Type	Description
region_idPK	INT	Unique region identifier
region_name	VARCHAR(100)	Sales region name

Your question is Top 5 Instruments by Region. Start with the requirements and the three tables in the Question tab.

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Problem