C02,C11,U01,U02,D02,D32,D45,D67

HouseID    FeatureID
1          C07
1          D67
2          D02

$string = 'C02,C11,U01,U02,D02,D32,D45,D67';
$array  = explode(',', $string);

$array_of_codes = explode(",", $db_return_string);