1:n relationship

DROP TABLE IF EXISTS product_details;
DROP TABLE IF EXISTS products;

CREATE TABLE IF NOT EXISTS products (
	productID    INT UNSIGNED  NOT NULL AUTO_INCREMENT,
	productCode  CHAR(3)       NOT NULL DEFAULT '',
	name         VARCHAR(30)   NOT NULL DEFAULT '',
	quantity     INT UNSIGNED  NOT NULL DEFAULT 0,
	price        DECIMAL(7,2)  NOT NULL DEFAULT 99999.99,
	-- supplierID   INT UNSIGNED  NOT NULL,
	PRIMARY KEY  (productID)
);
CREATE TABLE IF NOT EXISTS product_details (
	productID  INT UNSIGNED   NOT NULL,
	comment    TEXT  NULL,
	PRIMARY KEY (productID),
	FOREIGN KEY (productID) REFERENCES products (productID)
);

ALTER TABLE products ADD COLUMN supplierID INT UNSIGNED NOT NULL;
ALTER TABLE products ADD FOREIGN KEY (supplierID) REFERENCES suppliers (supplierID);

mysql -u root -p example_db < example_db.sql
Enter password:

ERROR 1005 (HY000) at line 26: Can't create table `example_db`.`#sql-1c5d_36` (errno: 150 "Foreign key constraint is incorrectly formed")