code: public String getParameterClassName(int param) throws SQLException {
  
          checkRange(param);
  
          return rmd.columnTypes[--param].getJDBCClassName();
      }
docs: Retrieves the fully-qualified name of the Java class whose instances
  should be passed to the method <code>PreparedStatement.setObject</code>.
  
  @param param the first parameter 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>PreparedStatement.setObject</code> to set the value
  in the specified parameter. This is the class name used
  for custom mapping.
  @exception SQLException if a database access error occurs
  @since JDK 1.4, HSQLDB 1.7.2