我有三张桌子。 Order
,Location
,Order_Location
其中,Order_Location
是具有多对多关系的表。Order
具有List<Location>
。 Location
具有称为city
的属性。我想使用HQL(Java的Hibernate 3.6)来获取特定订单的所有位置,并按city
进行排序。
在hbm文件中,List<Location>
是使用idbag映射的。尽管我得到了HQL,但生成的SQL查询却两次连接到Location
和Order_Location
表,这对我来说很麻烦。
我在这里做错了什么?
SELECT o.locationList FROM Order o
join o.locationList locList
where o.orderId = 1
order by locList.city desc
转换为以下内容
select
order4_.LOC_ID as order1_355_,
order4_.LOC_CODE as order2_355_,
order4_.CITY as order3_355_,
order4_.CITY_LONG_NAME as order4_355_
from
sche.order order0_
inner join
sche.order_location order1_
on order0_.ORDER_ID=order1_.ORDER_ID
inner join
sche.location order2_
on order1_.LOC_ID=order2_.LOC_ID
inner join
sche.order_location order3_
on order0_.ORDER_ID=order3_.ORDER_ID
inner join
sche.location order4_
on order3_.LOC_ID=order4_.LOC_ID
where
order0_.ORDER_ID=1
order by
order2_.city desc
=========编辑
Order.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"
>
<hibernate-mapping>
<class name="collectionorderby.Order" table="ORDER">
<id name="orderId" type="string">
<column name="ORDER_ID" length="32" />
<generator class="uuid" />
</id>
<idbag name="locationList" lazy="false" table="ORDER_LOCATION" fetch="select">
<collection-id column="ORDER_LOCATION_ID" type="string">
<generator class="uuid" />
</collection-id>
<key>
<column name="ORDER_ID" length="32" not-null="true" />
</key>
<many-to-many column="LOC_ID" class="collectionorderby.Location"
fetch="join" />
</idbag>
</class>
</hibernate-mapping>
Location.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping>
<class name="collectionorderby.Location" table="LOCATION">
<id name="locId" type="string">
<column name="LOC_ID" length="50" />
</id>
<property name="locCode" type="string">
<column name="LOC_CODE" length="50" />
</property>
<property name="city" type="string">
<column name="CITY" length="50" />
</property>
<property name="cityLongName" type="string">
<column name="CITY_LONG_NAME" length="500" />
</property>
</class>
</hibernate-mapping>
====编辑
注意,当我们提供
order by
时,转换后的查询从表的第一个实例获取select
,而order by
是使用表的第二个实例完成的。我想,如果我们避免这些表的重复实例,那将不会发生。 最佳答案
以下工作按预期方式进行。在选择中使用别名locList
代替o.locationList
SELECT locList FROM Order o join o.locationList locList where o.orderId = 1 order by locList.city desc