INSERT INTO orders (order_id, product_id, quantity, client_id, seller_id)
VALUES
('1','8','2','3','6'),
('2','5','3','1','1'),
('3','1','4','2','1');

SELECT product_id, client_id, seller_id, quantity
INTO @product_calc, @client_calc, @seller_calc, @quantity_calc
FROM orders
WHERE order_id = 1;

SELECT seller_state INTO @seller_state_calc FROM seller_member WHERE member_id = @seller_calc;

SELECT client_state INTO @client_state_calc FROM clients WHERE client_id = @client_calc;

SELECT shipping_price INTO @shipping_calc FROM shipping WHERE seller_state = @selller_state_calc and client_state = @client_state_calc;