How to create a foreign key in phpmyadmin

You can do it the old fashioned way... with an SQL statement that looks something like this

ALTER TABLE table_1_name
    ADD CONSTRAINT fk_foreign_key_name
    FOREIGN KEY (table_1_column_name)
    REFERENCES target_table(target_table_column_name);

For example: If you have books table with column created_by which refers to column id in users table:

ALTER TABLE books
    ADD CONSTRAINT books_FK_1
    FOREIGN KEY (created_by)
    REFERENCES users(id);

This assumes the keys already exist in the relevant table

The key must be indexed to apply foreign key constraint. To do that follow the steps.

1. Open table structure. (2nd tab)
2. See the last column action where multiples action options are there. Click on Index, this will make the column indexed.
3. Open relation view and add foreign key constraint.

You will be able to assign DOCTOR_ID as foreign now.

To be able to create a relation, the table Storage Engine must be InnoDB. You can edit in Operations tab.

Then, you need to be sure that the id column in your main table has been indexed. It should appear at Index section in Structure tab.

Finally, you could see the option Relations View in Structure tab. When edditing, you will be able to select the parent column in foreign table to create the relation.

See attachments. I hope this could be useful for anyone.