public void addHandler(String columnName,SQLDataHandler handler){
  if (m_overrides == null)   m_overrides=new HashMap(3);
  m_overrides.put(columnName,handler);
}

public void addHandler ( String columnName , SQLDataHandler handler ) { if ( m_overrides == null ) m_overrides = new HashMap ( 3 ) ; m_overrides . put ( columnName , handler ) ; }
add a custom data handler for a given column name .
