While trying to update rows using a DataSet the following exception appears :

java.sql.SQLRuntimeException: DataSet cannot be modified.

Using build 80 of mustang and today's official Trondheim build of the Derby trunk.

Code :

 Here's the method that's doing the updating:

    /**
      * Updates a list of addresses using DataSet
      */
    public void updateAddresses()
        throws SQLException {
        AddressQueryIdSubset aq =
                con.createQueryObject(AddressQueryIdSubset.class);
        DataSet<Address> addresses = aq.getAddresses();
        if (addresses.isReadOnly())
            throw new SQLException("DataSet is readOnly!");
        for (Address val : addresses) {
            val.setCity("Davis");
            addresses.modify(); // [Exception thrown here]
        }
        aq.close();
    }

 And here's the query interface:

 public interface AddressQueryIdSubset extends BaseQuery {

    @Select(readOnly=false,
            sql="SELECT addrid, street, city, state, zipcode, country"
           + " FROM addresses WHERE datastore_identity < 5")
    DataSet<Address> getAddresses();
 }