Referencing wp_users

Hi Guys,

I am trying to link a foreign key to the wp_users ID column but mysql keeps telling me that I am using the wrong syntax between ‘REFERENCES wp_users(ID)’

Table below:

CREATE TABLE my_comments (
comment_id integer auto_increment NOT NULL,
comment_target_id integer NOT NULL,
comment_target_tablename varchar(120) NOT NULL,
comment_author varchar(120) NOT NULL,
comment_date date NOT NULL,
comment_content text NOT NULL,
comment_approved tinyint(1) NOT NULL,
comment_author_ip_address varchar(30) NOT NULL,
user_id integer NOT NULL,
PRIMARY KEY(comment_id),
FOREIGN KEY user_id REFERENCES wp_users(ID)
);