Trouble getting my primary and foreign key to work - mysql

Question

I keep getting errors when I try to run the relational part of the database to pull the 3 columns in the relation table from the customer table and bill table.
DROP DATABASE IF EXISTS CreateDB2;
CREATE DATABASE CreateDB2;
USE CreateDB2;
CREATE TABLE `tbl_employee` (
`tbl_EmployeeName` varchar(20) NOT NULL,
`tbl_Department` varchar(15) NOT NULL,
`employee_id` int(11) NOT NULL AUTO_INCREMENT,
`department_location` varchar(20) NOT NULL,
`department_name` varchar(15) NOT NULL,
`supervisor` varchar(15) NOT NULL,
PRIMARY KEY (`employee_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
CREATE TABLE `customer` (
`c_ID` varchar(15) NOT NULL,
`c_address` varchar(50) NOT NULL,
`c_Time` time NOT NULL,
`c_order` int(100) NOT NULL,
PRIMARY KEY (`c_ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
CREATE TABLE `bill` (
`b_items` double DEFAULT NULL,
`b_price` double DEFAULT NULL,
`b_discount` double DEFAULT NULL,
`b_deliveryFee` double DEFAULT NULL,
`b_tax` double DEFAULT NULL,
`b_tip` double DEFAULT NULL,
`b_total` double NOT NULL,
`quantity` int(11) NOT NULL,
PRIMARY KEY (`b_total`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
CREATE TABLE `food` (
`code` int(11) NOT NULL AUTO_INCREMENT,
`f_catagory` varchar(20) NOT NULL,
`f_item` varchar(10) NOT NULL,
`f_info` varchar(50) NOT NULL,
`f_price` int(11) NOT NULL,
PRIMARY KEY (`code`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
CREATE TABLE `restaurantinfo` (
`name` varchar(20) NOT NULL,
`address` varchar(50) DEFAULT NULL,
`phone` int(13) DEFAULT NULL,
`email` varchar(20) DEFAULT NULL,
PRIMARY KEY (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
CREATE TABLE `relationaltable` (
`c_ID` varchar(15) NOT NULL,
`c_order` int(100) NOT NULL,
`b_total` double NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
ALTER TABLE `customer` ADD CONSTRAINT `c_ID` FOREIGN KEY (`c_ID`) REFERENCES `relationaltable`(`c_ID`) ON DELETE RESTRICT ON UPDATE RESTRICT;
ALTER TABLE `order` ADD CONSTRAINT `c_order` FOREIGN KEY (`c_order`) REFERENCES `relationaltable`(`c_order`) ON DELETE RESTRICT ON UPDATE RESTRICT;
ALTER TABLE `bill` ADD CONSTRAINT `b_total` FOREIGN KEY (`b_total`) REFERENCES `relationaltable`(`b_total`) ON DELETE RESTRICT ON UPDATE RESTRICT;
On the last part here, it is not working. It gives error code 1005
The alter table at the bottom is the probably the issue. I am just not sure how to fix it. Any help is appreciated. Thanks.

Answer 1

The foreign key is incorrectly formed.
You connect customer.c_ID should be equal to relationaltable.c_order
customer.c_ID is varchar(15) NOT NULL
relationaltable.c_order is int(100) NOT NULL
The data type and also the length has to be matching