Table schema:
CREATE TABLE products (product_name VARCHAR, product_id VARCHAR); CREATE TABLE orders (customer_id VARCHAR, order_id VARCHAR); CREATE TABLE customers (customer_name VARCHAR, customer_id VARCHAR); CREATE TABLE order_items (product_id VARCHAR, order_id VARCHAR)

Question: List the names of the customers who have once bought product "food".
SQL: SELECT T1.customer_name FROM customers AS T1 JOIN orders AS T2 JOIN order_items AS T3 JOIN products AS T4 ON T1.customer_id = T2.customer_id AND T2.order_id = T3.order_id AND T3.product_id = T4.product_id WHERE T4.product_name = "food" GROUP BY T1.customer_id HAVING COUNT(*) >= 1