รบกวนช่วยเหลือหน่อยครับ ผมอยากกำหนดforeign key ใน xampp แบบcode รบกวนหน่อยนะคับ

CREATE TABLE `Customers` (
`Customer_ID` int(10) NOT NULL AUTO_INCREMENT,
`C_User` varchar(50) NOT NULL,
`C_Password` varchar(50) NOT NULL,
`C_Career` varchar(100) NOT NULL,
`C_Tel` int(10) NOT NULL,
`C_Address` varchar(200) NOT NULL,
PRIMARY KEY (`Customer_ID`)
) ENGINE=INNODB DEFAULT CHARSET=UTF8 AUTO_INCREMENT=1 ;

CREATE TABLE `CasioWatch` (
`Casio_ID` int(10) NOT NULL AUTO_INCREMENT,
`Ca_Name` varchar(100) NOT NULL,
`Ca_Price` int(20) NOT NULL,
`Ca_Detail` varchar(1000) NOT NULL,
`Customer_ID` int(10) NOT NULL,
`Sales_ID` int(10) NOT NULL,
PRIMARY KEY (`Casio_ID`)
FOREIGN KEY ('Customer_ID') REFERENCES  ('Customer_ID')
) ENGINE=INNODB DEFAULT CHARSET=UTF8 AUTO_INCREMENT=1 ;

CREATE TABLE `Salesman` (
`Sales_ID` int(10) NOT NULL AUTO_INCREMENT,
`S_User` varchar(50) NOT NULL,
`S_Password` varchar(50) NOT NULL,
`S_NickName` varchar(10) NOT NULL,
`S_Age` int(3) NOT NULL,
`S_Tel` int(10) NOT NULL,
`S_Email` varchar(50) NOT NULL,
`S_Address` varchar(200) NOT NULL,
PRIMARY KEY (`Sales_ID`)
) ENGINE=INNODB DEFAULT CHARSET=UTF8 AUTO_INCREMENT=1 ;