Join Choice and Analytical Integrity | Dataford Interview Questions

Explain the difference between a left join and an inner join, and describe a scenario where using the wrong join would corrupt your analytical results.

Use the provided customer and order data to demonstrate the distinction with a result that preserves customers who have no orders. Explain how the alternative join could change the analysis.

Output

One row per customer, including customers without orders
Columns: customer_id, customer_name, order_count, total_revenue, and order_status
Sort by customer_id ascending

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(100)	Customer display name
region	VARCHAR(50)	Customer geographic region

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	Customer associated with the order
amount	NUMERIC(10,2)	Order revenue amount
order_date	DATE	Date the order was placed

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Problem