DELIMITER $$
CREATE FUNCTION Days (s_date DATE, e_date DATE) RETURNS INT BEGIN
IF (e_date IS NULL) THEN
RETURN DATEDIFF(CURDATE(), s_date);
ELSE
RETURN DATEDIFF(e_date, s_date);
END IF; END $$
DELIMITER ;
SELECT FIO, Days(Settlement_date, Guests) FROM Guests;
DELIMITER $$
CREATE PROCEDURE Cheque (passport VARCHAR(10)) BEGIN
SELECT FIO, Settlement_date, Eviction_date, Room, Rooms.Class, COST * Days(Settlement_date, Eviction_date)

1
FROM Guests, Rooms, Room_Classes
WHERE Guests.Passport = passport AND Guests.Room = Rooms.ID AND Rooms.Class = Room_Classes.Class;
SELECT Service, Amount, COST FROM Provide_Services WHERE Guest = passport;
SELECT SUM(Provide_Services.COST) + (COST * Days(Settlement_date, Eviction_date)) AS 'Общая стоимость'
FROM Provide_Services, Guests
WHERE Provide_Services.Guest = passport AND Guests.Passport = passport;
END $$
DELIMITER ;
CALL Cheque('aaaabbbbcc');