ระบุชื่อลูกค้าที่เคยซื้อผลิตภัณฑ์ "อาหาร"
List the names of the customers who have once bought product "food".
df_products = pd.DataFrame(columns=['product_name', 'product_id']); df_orders = pd.DataFrame(columns=['customer_id', 'order_id']); df_customers = pd.DataFrame(columns=['customer_name', 'customer_id']); df_order_items = pd.DataFrame(columns=['product_id', 'order_id'])
df_customers[df_customers.customer_id.isin(df_orders[df_orders.order_id.isin(df_order_items[df_order_items.product_id.isin(df_products[df_products.product_name=='food'].product_id)].order_id)].customer_id)].customer_name