code: private void checkColumn(int column) throws SQLException {
  
          if (column < 1 || column > columnCount) {
              throw Util.sqlException(ErrorCode.JDBC_COLUMN_NOT_FOUND,
                                      String.valueOf(column));
          }
      }
docs: Performs an internal check for column index validity. <p>
  
  @param column index of column to check
  @throws SQLException when this object's parent ResultSet has
  no such column