Week-over-Week Shipment Volume Changes | Dataford Interview Questions

How would you write a SQL query to compare week-over-week shipment volume and identify the largest changes by region at Walmart Supply Chain?

Use the provided shipment and fulfillment center data. Compare each region only for weeks that have a preceding regional week, and exclude cancelled shipments.

Output

One row per region and comparable week, with region, week_start, current_volume, prior_week_volume, volume_change, and percent_change.
Include only regions with shipment data in both the current and preceding week.
Sort by largest absolute volume change descending, then region ascending and week descending.

Schema

shipments

Column	Type	Description
shipment_idPK	INT	Unique shipment identifier
facility_id	INT	Fulfillment center associated with the shipment
shipment_date	DATE	Date the shipment was recorded
shipment_status	VARCHAR(30)	Current shipment status

fulfillment_centers

Column	Type	Description
facility_idPK	INT	Unique fulfillment center identifier
facility_code	VARCHAR(20)	Operational facility code
region	VARCHAR(30)	Supply chain region

Your question is Week-over-Week Shipment Volume Changes. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem