hibernate映射视图的两种方式

1.数据库已经建立视图，hibernate只是把视图当作普通的表来映射。
视图VIEW_MER_INST_POS:
select MER.DAYS_MERCHT_ID MER_ID,
       INST.DAYS_MERCHT_ID INST_ID,
       POS.POS_ID POS_ID
from tbl_days_mercht_attr MER,
     tbl_days_mercht_info INST,
     tbl_days_mercht_pos_info POS
where MER.days_mercht_id = INST.up_days_mercht_id
  and INST.days_mercht_id = POS.days_mercht_id

hbm.xml配置
<class
    name="db.po.ViewMerInstPos"
    table="VIEW_MER_INST_POS"
>

    <composite-id>
            <key-property
            name="merId"
            column="MER_ID"
            type="java.lang.String"
            length="8"
        />
        <key-property
            name="instId"
            column="INST_ID"
            type="java.lang.String"
            length="8"
        />
        <key-property
            name="posId"
            column="POS_ID"
            type="java.lang.String"
            length="8"
        />
  </class>
</hibernate-mapping>

2.数据库没有视图，用hibernate自己做视图映射
hbm配置如下：
<hibernate-mapping package="huntersxp.db.pojo">
<class name="ViewMerInstPos">
<meta attribute="sync-DAO">false</meta>
<subselect>
select
MER.DAYS_MERCHT_ID MER_ID,INST.SHOP_NM SHOP_NM,POS.POS_ID POS_ID
from tbl_days_mercht_attr MER,
tbl_days_mercht_info INST,
tbl_days_mercht_pos_info POS
where MER.days_mercht_id = INST.up_days_mercht_id and INST.days_mercht_id = POS.days_mercht_id
</subselect>
<synchronize table="tbl_days_mercht_attr"/>
<synchronize table="tbl_days_mercht_info"/>
<synchronize table="tbl_days_mercht_pos_info"/>
<composite-id>
        <key-property
            name="merId"
            column="MER_ID"
            type="java.lang.String"
            length="8"
        />
        <key-property
            name="shopNm"
            column="SHOP_NM"
            type="java.lang.String"
            length="40"
        />
        <key-property
            name="posId"
            column="POS_ID"
            type="java.lang.String"
            length="40"
        />
</composite-id>
</class>
</hibernate-mapping>
其中synchronize表示当表的数据发生变化的时候，视图的数据也会发生变化。