-- Database schema
| Products : product_id [ INT ] primary_key , product_name [ TEXT ] , product_price [ INT ] , product_description [ TEXT ] | Addresses : address_id [ INT ] primary_key , address_details [ TEXT ] , city [ TEXT ] , zip_postcode [ TEXT ] , state_province_county [ TEXT ] , country [ TEXT ] | Customers : customer_id [ INT ] primary_key , payment_method [ TEXT ] , customer_name [ TEXT ] , customer_phone [ TEXT ] , customer_email [ TEXT ] , date_became_customer [ TEXT ] | Regular_Orders : regular_order_id [ INT ] primary_key , distributer_id [ INT ] Regular_Orders.distributer_id = Customers.customer_id | Regular_Order_Products : regular_order_id [ INT ] Regular_Order_Products.regular_order_id = Regular_Orders.regular_order_id , product_id [ INT ] Regular_Order_Products.product_id = Products.product_id | Actual_Orders : actual_order_id [ INT ] primary_key , order_status_code [ TEXT ] , regular_order_id [ INT ] Actual_Orders.regular_order_id = Regular_Orders.regular_order_id , actual_order_date [ TEXT ] | Actual_Order_Products : actual_order_id [ INT ] Actual_Order_Products.actual_order_id = Actual_Orders.actual_order_id , product_id [ INT ] Actual_Order_Products.product_id = Products.product_id | Customer_Addresses : customer_id [ INT ] Customer_Addresses.customer_id = Customers.customer_id , address_id [ INT ] Customer_Addresses.address_id = Addresses.address_id , date_from [ TEXT ] , address_type [ TEXT ] , date_to [ TEXT ] | Delivery_Routes : route_id [ INT ] primary_key , route_name [ TEXT ] , other_route_details [ TEXT ] | Delivery_Route_Locations : location_code [ TEXT ] primary_key , route_id [ INT ] Delivery_Route_Locations.route_id = Delivery_Routes.route_id , location_address_id [ INT ] Delivery_Route_Locations.location_address_id = Addresses.address_id , location_name [ TEXT ] | Trucks : truck_id [ INT ] primary_key , truck_licence_number [ TEXT ] , truck_details [ TEXT ] | Employees : employee_id [ INT ] primary_key , employee_address_id [ INT ] Employees.employee_address_id = Addresses.address_id , employee_name [ TEXT ] , employee_phone [ TEXT ] | Order_Deliveries : location_code [ TEXT ] Order_Deliveries.location_code = Delivery_Route_Locations.location_code , actual_order_id [ INT ] Order_Deliveries.actual_order_id = Actual_Orders.actual_order_id , delivery_status_code [ TEXT ] , driver_employee_id [ INT ] Order_Deliveries.driver_employee_id = Employees.employee_id , truck_id [ INT ] Order_Deliveries.truck_id = Trucks.truck_id , delivery_date [ TEXT ] |
-- -- How many different payment methods are there?

SELECT count(DISTINCT payment_method) FROM customers;