Untitled

CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_create_bill`(
		IN p_StaffId VARCHAR(10), 
		IN p_OrderCusomerId INT, 
		IN p_Tax VARCHAR(20), 
		IN p_FristName VARCHAR(50), 
		IN p_LastName VARCHAR(50)
    )
BEGIN
	DECLARE OldBillId INT;
    
    SELECT BillId INTO OldBillId FROM bill WHERE CustomerOrderId = p_OrderCusomerId;
    
    IF(OldBillId IS NULL) THEN
		INSERT INTO bill (CreateDate, Tax, FristName, LastName, CustomerOrderId, StaffId)
        VALUES (NOW(), p_Tax, p_FristName, p_LastName, p_OrderCusomerId, p_StaffId);
        
		SELECT LAST_INSERT_ID() AS BillId;
	ELSE 
		SELECT OldBillId AS BillId;
	END IF;
END