Database Queries and Data Understanding | Dataford Interview Questions

Describe how you approach database queries and understanding data and databases as a data engineer.

Demonstrate your approach by producing a customer-level summary from the provided relational data. Include customers without qualifying records and identify records where a completed order has a missing amount.

Output

One row per customer, ordered by customer_id ascending
Columns: customer_id, customer_name, completed_order_count, completed_revenue, latest_completed_order, and data_quality_flag
Include all customers, including those with no completed orders

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(100)	Customer display name

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	Customer associated with the order
order_date	DATE	Date on which the order was placed
status	VARCHAR(20)	Order processing status
amount	NUMERIC(10,2)	Order amount

Your question is Database Queries and Data Understanding. Start with the requirements and the two tables in the Question tab.

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Problem