java - Hibernate 在同一张表上使用多个连接

Question

我有两个 postgreSQL 表 preference and date_etl 和 preference_date_etl 存储它们的映射。

preference_date_etl 的 hibernate 映射:

<hibernate-mapping>

    <class name="com..bla.bla.PreferenceDateETL"
        table="preference_date_etl">
        <id name="id" column="id" unsaved-value="null">
            <generator class="sequence">
                <param name="sequence">
            <![CDATA[preference_date_etl_id_seq]]>
                </param>
            </generator>
        </id>

        ...things....
    </class>
</hibernate-mapping>

所以现在当我执行如下 HQL 时:

select distinct pd.preference from PreferenceDateETL pd where pd.corporation.id=:corporationId and pd.preference.employee.deleted=false and pd.deleted=false and pd.preference.deleted=false  and  pd.dateETL.localDate>=:startDM and pd.dateETL.localDate<=:endDM and pd.preference.approvalStatus!=:approvalStatus order by pd.preference.dateCreated

转换为 SQL:

select
        distinct preference1_.id as id1_76_,
        ....things...
    from
        preference_date_etl preference0_ 
    inner join
        preference preference1_ 
            on preference0_.preference_id=preference1_.id cross 
    join
        preference preference2_ cross 
    join
        employee employee3_ cross 
    join
        date_etl dateetl5_ 
    where
        ...things... 
    order by
        preference2_.date_created

问题:preference2_.date_created in order by 子句不在选择列表中，因此异常 SELECT DISTINCT，ORDER BY 表达式必须出现在选择列表中。

问题:为什么 hibernate 在同一个表上使用两个连接 INNER 和 CROSS。如果 ORDER BY 列表中有 preference1_.date_created 那么一切都会很好。想法？

Answer 1

您可以重构此查询以避免使用 distinct 关键字，从而毫无问题地对结果进行排序。为此，请将 PreferenceDateETL 对象的条件设为子查询，然后检索链接到子查询中的 PreferenceDateETL 对象的偏好对象组中的所有 Preference 对象。这是 HQL:

from Preference p where p in 
  (select pd.preference from PreferenceDateETL pd
  where pd.corporation.id=:corporationId
  and pd.deleted=false
  and pd.dateETL.localDate>=:startDM
  and pd.dateETL.localDate<=:endDM)
and p.employee.deleted=false
and p.deleted=false
and p.approvalStatus != :approvalStatus
order by p.dateCreated