SELECT customer_details FROM customers EXCEPT SELECT t2.customer_details FROM policies AS t1 JOIN customers AS t2 ON t1.customer_id  =  t2.customer_id
What are the names of customers who do not have any policies?
SELECT customer_details FROM customers EXCEPT SELECT t2.customer_details FROM policies AS t1 JOIN customers AS t2 ON t1.customer_id = t2.customer_id
select customer_details from customers except select t2 . customer_details from policies as t1 join customers as t2 on t1 . customer_id = t2 . customer_id
What are the names of customers who do not have any policies ?