Table schema:
CREATE TABLE first_notification_of_loss (customer_id VARCHAR, service_id VARCHAR); CREATE TABLE customers (customer_name VARCHAR, customer_id VARCHAR); CREATE TABLE services (service_id VARCHAR, service_name VARCHAR)

Question: Find the names of customers who have used either the service "Close a policy" or the service "Upgrade a policy".
SQL: SELECT t1.customer_name FROM customers AS t1 JOIN first_notification_of_loss AS t2 ON t1.customer_id = t2.customer_id JOIN services AS t3 ON t2.service_id = t3.service_id WHERE t3.service_name = "Close a policy" OR t3.service_name = "Upgrade a policy"