issue with adding mysql FOREIGN KEY to a table

I have a problem to add a Foreign key to a table. I have tried

ALTER TABLE Child
ADD FOREIGN KEY (pc_id)
REFERENCES Parent_Carer(pc_id);

, but it does not add the key. The structure:

CREATE TABLE Parent_Carer (
pc_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
pc_title CHAR(5) NOT NULL,
pc_fname VARCHAR(15) NOT NULL,
pc_lname VARCHAR(20) NOT NULL,
pc_phone VARCHAR(15) NOT NULL,
pc_address1 VARCHAR(25) NOT NULL,
pc_address2 VAR开发者_如何学运维CHAR(25) NOT NULL,
pc_town VARCHAR(35) NOT NULL,
pc_postcode VARCHAR(15) NOT NULL) ;


CREATE TABLE Child(
child_id INT AUTO_INCREMENT PRIMARY KEY NOT NULL,
pc_id INT NOT NULL,
child_fname VARCHAR(20) NOT NULL,
child_lname VARCHAR(20) NOT NULL,
child_dob DATE NOT NULL,
child_gender ENUM ('F','M') DEFAULT 'F' NOT NULL);

Thank you.

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What are you using to display the Foreign Key? You need to use one of the following:

SHOW CREATE TABLE tbl_name;

or

SHOW TABLE STATUS FROM db_name LIKE 'tbl_name';

Reference