I have a theoretical question.
I can\'t see any difference between declaring a function within a PHP file and creating a stored procedure in a dat
Short answer would be if you want code to be portable, don't use stored procedures because if you will want at some point change database for example from MySQL to PostgreSQL you will have to update/port all stored procedures you have written.
On the other hand, sometimes you can achieve better performance results using stored procedures because all that code will run by database engine. You also can make situation worse if stored procedures will be used improperly.
I dont think that selecting country is very expensive operation. So I guess you don't have to use stored procedures for this case.