final String INSERTFROM = "INSERT INTO priorities " +
                          "(callId, priorityNum, employeeCod) " +
                          "SELECT callId, priorityNum, employeeCod " +
                          "FROM calls WHERE callId=?"; // note WHERE here

@Override
public void insert(Priority o) throws DAOException {
    try{
       pstm = con.prepareStatement(INSERTFROM);
       /* / error under */
       pstm.setInt(1, o.getCallId());
       // no need in setting other values, since they are copied
       // from the calls table

       if(pstm.executeUpdate() == 0 ){
          throw new DAOException("The update couldn't been saved");
       }
    } catch (SQLException ex) {
     /* And it stops here */
        throw new DAOException("SQL Error", ex);
    } finally {
       if(pstm != null){
           try {
               pstm.close();
           } catch (SQLException ex) {
               throw new DAOException("Error to close connection", ex);
           }
       }
    }
}