prop2db = new Hashtable (); db2prop = new Hashtable ();
prop2db = new HashMap (); db2prop = new HashMap ();
    public DbMapping (Application app) {	this.app = app;	prop2db = new Hashtable ();	db2prop = new Hashtable ();	parent = null;	// subnodes = null;	// properties = null;	idField = "id";    }