SELECT count(DISTINCT customer_id) FROM customer_orders WHERE order_status  =  "Cancelled"
How many customers have at least one order with status "Cancelled"?
SELECT count ( DISTINCT customer_id ) FROM customer_orders WHERE order_status = `` Cancelled ''
select count ( distinct customer_id ) from customer_orders where order_status = value
How many customers have at least one order with status `` Cancelled '' ?