conditional update

hi

I have two tables.. 

1. csv_country (country_code      varchar2(2) , country_name      varchar2(255) 

2. country     (country_code      varchar2(2) , country_name      varchar2(255) 

now. i want to update country table with below condition..

if country.country_name = csv.country_name then 

if country.country_code != csv.country_code  then

   update country set country_code = csv.country_code  where country.country_name=csv.country_name;

end if;

else

insert into country select * from csv_country.

how to write pl/sql or sql for above requirement.

Thanks,

Rajesh