Hibernate不支持left join带on的条件查询。
解决办法：使用原生SQL或者使用HQL方式需要修改hbm文件(如果项目中大部分不适用级联配置情况下)
需求是查询网络信息，网络信息中关联了分区、网络IP(1个网络－－Ｎ个网络ＩＰ)，网桥信息.
HQL：
public void queryVnets(Page page) {
StringBuffer hql = new StringBuffer();
hql.append("select new Map(vn.id as id, vn.vnName as vnName, b.name as vnType, ");
hql.append("vn.vnIptype as vnIptype, vn.vnIp as vnIp,vn.vnNat as vnNat, vn.vnFlag as vnFlag, ");
hql.append("vn.vnetFlag as vnetFlag, (case when sum(vmvn.state)='0' then 0 else 1 end) as vnState, ");
hql.append("vn.useType as useType, vn.createTime as createTime, ");
hql .append("zone.oneName as oneName, zone.oneHypervisor as oneHypervisor, zone.oneSeq as oneSeq) ");
hql.append("from VnetTable vn, ZoneTable zone, BridgeTable b ");
hql.append("left join fetch vn.VnTables vmvn where zone.id = vn.zoneId and vn.vnType = b.id ");
... ...
hql.append(" group by vn.id");
if (vnState != null && !"".equals(vnState)) {
if ("0".equals(vnState)) {
hql.append(" having sum(vmvn.state)=0");
} else if ("1".equals(vnState)) {
hql.append(" having sum(vmvn.state)!=0");
}
}
}
hbm配置文件：
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
<
class name="com.base.mapping.VnetTable" table="vnet_table" >
<id name="id" type="java.lang.String">
<column name="ID" length="32" />
<generator
class="uuid.hex" />
</id>
<property name="vnId" type="java.lang.Long">
<column name="VN_ID">
<comment>创建虚拟网络时得到的ID</comment>
</column>
</property>
...
<property name="zoneId" type="java.lang.String">
<column name="ZONE_ID" length="32">
<comment>分区ID</comment>
</column>
</property>
<property name="vlanId" type="java.lang.Integer">
<column name="VLAN_ID">
<comment>VLAN_ID</comment>
</column>
</property>
<set name="vnTables" lazy="false" order-by="id asc" inverse="false" fetch="join" cascade="all"> <key column="VN_NID"/>
<one-to-many
class="com.base.mapping.VnTable"/>
</set>
</
class>
</hibernate-mapping>
理解inverse和cascade，可以参考：http://blog.csdn.net/wkcgy/article/details/6271321
总结： <one-to-many>中，建议inverse=”true”，由“many”方来进行关联关系的维护 <many-to-many>中，只设置其中一方inverse=”false”，或双方都不设置 Cascade，通常情况下都不会使用。特别是删除，一定要慎重。操作建议
一般对many-to-one和many-to-many不设置级联，这要看业务逻辑的需要;对one-to-one和one-to-many设置级联。 many-to-many关联关系中，一端设置inverse=”false”，另一端设置为inverse=”true”。在one-to-many关联关系中，设置inverse=”true”,由多端来维护关系表
posted on 2013-09-12 11:57
David1228 阅读(16662)
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