Previously my all queries were running fine in CI version 2.0 but when I upgraded to 2.0.3 some of my SELECT queries were broken.
CI is adding
All other answers are really old, this one works with CI 2.1.4
// set this to false so that _protect_identifiers skips escaping:
$this->db->_protect_identifiers = FALSE;
// your order_by line:
$this -> db -> order_by('FIELD ( products.country_id, 2, 0, 1 )');
// important to set this back to TRUE or ALL of your queries from now on will be non-escaped:
$this->db->_protect_identifiers = TRUE;