Answers for "how to make something a foreign key in phpmyadmin"

create foreign key phpmyadmin

ALTER TABLE table_name
ADD CONSTRAINT fk_foreign_key_name
FOREIGN KEY (foreign_key_name)
REFERENCES target_table(target_key_name);

phpmyadmin add foreign key

ALTER TABLE table_name
    ADD CONSTRAINT fk_foreign_key_name
    FOREIGN KEY (foreign_key_name)
    REFERENCES target_table(target_key_name);