CREATE TABLE customer_addresses (customer_id VARCHAR2, address_id VARCHAR2)
CREATE TABLE customers (customer_id VARCHAR2)
CREATE TABLE addresses (city VARCHAR2, address_id VARCHAR2)

Find the list of cities that no customer is living in.
SELECT city FROM addresses WHERE NOT city IN (SELECT DISTINCT t3.city FROM customers AS t1 JOIN customer_addresses AS t2 ON t1.customer_id = t2.customer_id JOIN addresses AS t3 ON t2.address_id = t3.address_id)
WITH "_u_0" AS (SELECT DISTINCT "t3"."city" FROM "customers" "t1" JOIN "customer_addresses" "t2" ON "t1"."customer_id" = "t2"."customer_id" JOIN "addresses" "t3" ON "t2"."address_id" = "t3"."address_id" GROUP BY "city") SELECT "city" FROM "addresses" LEFT JOIN "_u_0" "_u_0" ON "_u_0"."" = "city" WHERE "_u_0"."" IS NULL