Query to ADD/SELECT values from an SQL

Hello.

I need a query that will RETRIEVE a value from a database if it is present, but if the data isn't present, then the data will be INSERTed into the table.

Either way, I need the row returned at the end of the query.

I can do SELECT queries, but I don't have a clue as to how to proceed with branching statements.

For example:

User runs a query for "Canada".
Canada exists in the database, so the database returns Canada along with its ID.

Next user runs a query for "Chile".
Chile isn't in the database so a record is created and the ID (an IDENTITY field) is returned.

Does anyone know how I may accomplish this?something like this:

create proc MyProc
(
 @.countryid int out,
 @.countryname nvarchar(50)
)
set @.countryid = -1
select @.countryid = CountryId
from MyTable
where CountryName = @.countryname
if (@.countryid = -1)
begin
 insert into MyTable (CountryName)
 values (@.countryname)
 select @.countryid = scope_identity()
end

|||or

IF NOT EXISTS ( Select countryId from from MyTable where CountryName = @.countryname)
 INSERT INTO MyTable (CountryName) values (@.countryname)

hth