Add Column View Button w/ 2 Variables

Hello!

I'm a little confused on how to add a second variable to my "view" button. Below is what I'm using, but I need to pass the ID and another ID as well.

$this->datatables->add_column('edit', '<a href="/provider/orders/view_order/$1">view</a>', 'ORDERS.ID');

I'm needing to add ORDERS.PATIENTID to it as well.