如何联接不同数据库的两个选择查询？

Question

我想将XY表中的XY_OBJECT加入到YX OBJECT中，并在XY数据库中获取与YX_OBJECTS相关的值。我似乎找不到一种方法来维护层次结构生成查询的完整性，同时获取与层次结构生成列表中所有EQ相关的工作数据。

SELECT -- GENERATES XY ASSOCIATED TO EQ
    XY_OBJECT AS POSITION,
    XY_PPM AS Work,
    XY_CLASS AS XY_CLASS,
    XY_PERSON AS XY_ASSIGNED,
    XY_SCHEDGRP AS XY_SCHEDULER,
    XY_DUE AS NEXT_DUE,
    XY_DEACTIVE AS DEACTIVED_DATE,
    XY_FREQ AS FREQUENCY,
    XY_PERIODUOM AS FREQ_UOM
    FROM    CAN_XYOBJECTS

(SELECT -- GENERATES EQUIPMENT LIST
        YX_MRC AS X_MRC,
        YX_PARENT AS X_PARENT,
        YX_CODE AS X_CODE,
        YX_DESC AS X_DESC,
        YX_CLASS AS X_CLASS,
        YX_COSTCODE AS X_COSTCODE,
        YX_STATUS AS X_STATUS,
        YX_COMMISS AS X_COMMISS,
        LEVEL
        FROM CAN_YXOBJECTS
     START WITH YX_PARENT IN
             (Select
            YX_CODE AS P_CODE
            From CAN_YXOBJECTS 
            Where YX_DESC Like '%GENDO%'
            AND YX_CLASS Like 'PLENT'
            AND YX_STATUS <> 'Q')
        CONNECT BY PRIOR YX_CODE = YX_PARENT)
        ORDER BY X_PARENT