SQL for Top Delivery Zones | Dataford Interview Questions

Write a SQL query to identify Delivery Hero India top-performing delivery zones based on order volume and time-to-delivery.

Use completed orders with valid delivery timestamps. Return all zones, with the strongest-performing zones first: higher completed order volume precedes lower average delivery time.

Output

One row per delivery zone with zone_id, zone_name, order_volume, avg_delivery_minutes, and performance_rank.
Include zones with no qualifying orders, and sort by performance_rank, then zone_id.

Schema

delivery_zones

Column	Type	Description
zone_idPK	INT	Unique delivery zone identifier
zone_name	VARCHAR(100)	Delivery zone name
city	VARCHAR(100)	Indian city containing the zone

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
zone_id	INT	Delivery zone associated with the order
status	VARCHAR(20)	Order lifecycle status
placed_at	TIMESTAMP	Order placement timestamp
delivered_at	TIMESTAMP	Order delivery timestamp

Your question is SQL for Top Delivery Zones. 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