how to create view for a node type which reference aother node type?

Description

create table {node_bm} (
        vid int(10) unsigned NOT NULL default '0',
        nid int(10) unsigned NOT NULL default '0',
        xyid int(10) unsigned NOT NULL default '0',
        foo varchar(32),
        primary key (vid,nid),
        key xyid(xyid)
);
create table {node_xy} (
        vid int(10) unsigned NOT NULL default '0',
        nid int(10) unsigned NOT NULL default '0',
        foo varchar(32),
        primary key (vid,nid)
);

xyid is a reference to other node type node_xy's nid;

I want list those fields : node_bm.foo,node_xy.title,node_xy.foo
how to write node_bm_views_tables()?
thx.