Customers with shipped orders

Return customer_id and country for customers who have at least one shipped order. Each customer should appear once. Order by customer_id.

WHERE EXISTS (SELECT 1 FROM orders o WHERE o.buyer_id = c.customer_id AND o.status = 'shipped').

Sample input

customersAll 6 customers (customer_id, country shown).

customer_id	country
1	US
2	null
3	GB
4	IN
6	GB

orders (shipped only)Shipped orders belong to buyers 1, 4, and 3.

order_id	buyer_id	status
1004	1	shipped
1008	4	shipped
1012	3	shipped

Expected output

Expected outputCustomers with at least one shipped order, each once (a correlated semi-join).

customer_id	country
1	US
3	GB
4	IN

Constraints

Use a correlated EXISTS subquery on orders (o.buyer_id = c.customer_id AND o.status = 'shipped'). Do not use a join that would multiply customer rows.

Expected skills

Correlated subqueries and semi-join reasoning.

SQL

AI evaluation

Run the SQL query to inspect preview rows.