SQL JOIN With Missing Values | Dataford Interview Questions

Write a SQL query involving a JOIN and handling missing values using IFNULL.

Asked in the Virtual Onsite stage. SQL question involving join operations and missing data handling.

Task

Use the tables below to return each order with its customer name and a fallback region when the customer region is missing.

Join orders to customers on customer_id.
Return order_id, order_date, customer_name, and region.
If customers.region is NULL, show 'Unknown' instead.
Keep orders even when the customer record is missing, and show 'Unknown Customer' for the name.

orders

Column	Type	Description
order_idPK	INT	Order identifier
customer_id	INT	References customers.customer_id
order_date	DATE	Date the order was placed

customers

Column	Type	Description
customer_idPK	INT	Customer identifier
customer_name	VARCHAR(100)	Customer name
region	VARCHAR(50)	Customer region, may be missing

Your question is SQL JOIN With Missing Values. Start with the requirements and the two tables in the Question tab.

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