UPPER Case Constraint

Folks,
what script must I use, as a part of CREATE TABLE, to automatically convert characters to UPPER case on insert?
I wrote <CHECK (country = UPPER (country)> in the CREATE TABLE, which was wrong,
because the values were still in the lower case.
The sample script is:

CREATE TABLE address
(street varchar(40),
city varchar(20),
state char (2),
zip varchar (10),
country varchar (20))

When a user types "Canada", I want the inserted value be "CANADA"

Any help is greatly appreciated.