code: public String getColumnClassName(int column) throws SQLException {
      ColumnInformation ci = getColumnInformation(column);
      ColumnType type = ci.getColumnType();
      return ColumnType
          .getClassName(type, (int) ci.getLength(), ci.isSigned(), ci.isBinary(), options);
    }
docs: Returns the fully-qualified name of the Java class whose instances are manufactured if the
  method
  <code>ResultSet.getObject</code> is called to retrieve a value from the column.
  <code>ResultSet.getObject</code>
  may return a subclass of the class returned by this method.
  
  @param column the first column is 1, the second is 2, ...
  @return the fully-qualified name of the class in the Java programming language that would be
  used by the method <code>ResultSet.getObject</code> to retrieve the value in the specified
  column. This is the class name used for custom mapping.
  @throws SQLException if a database access error occurs