Is there any support for this:

http://www.w3resource.com/PostgreSQL/unique.php

CREATE TABLE orders(
ord_no integer,
ord_date date,
item_name character(35),
item_grade character(1),
ord_qty numeric,
ord_amount numeric,
UNIQUE (ord_no)
);

this don't do what i expected:
->addIndex(array("ord_no"), array('unique' => true))