I need to retreive rows based on an expression,

here is the case

id name countrycode
1 joe CA
2 mark FR
3 max XX


i need a query that will look for an entry where countrycode=CA, if nothin exist, it will return XX

for instance, if i ask the name where countrycode=CA, it will return joe. If i as a name where the countrycode=US, it will return max.

Can someone tell me how i can exprees that inside one query

Regards