在Hibernate Criteria API中使用subselect进行NULL处理

Question

我正在构建一个Hibernate Criterion,使用如下的子选择

DetachedCriteria subselect =
    DetachedCriteria.forClass(NhmCode.class, "sub"); // the subselect selecting the maximum 'validFrom'
subselect.add(Restrictions.le("validFrom", new Date())); // it should be in the past (null needs handling here)
subselect.add(Property.forName("sub.lifeCycle").eqProperty("this.id")); // join to owning entity
subselect.setProjection(Projections.max("validFrom"));  // we are only interested in the maximum validFrom

Conjunction resultCriterion = Restrictions.conjunction();
resultCriterion.add(Restrictions.ilike(property, value)); // I have other Restrictions as well
resultCriterion.add(Property.forName("validFrom").eq(subselect)); // this fails when validFrom and the subselect return NULL

return resultCriterion;

到目前为止它工作正常,但当validFrom和subselect导致NULL时,对return语句之前的最后一行的限制为false.

我需要的是一个处理这种情况的版本.可能通过应用NVL或合并或类似.

我该怎么做呢？

更新:----------------------------

带有sqlRestriction的Péters想法导致如下的where子句:

        ...
        and (
            nhmcode1_.valid_from = (
                select
                    max(sub_.valid_from) as y0_ 
                from
                    nhm_code sub_ 
                where
                    sub_.valid_from<=? 
                    and sub_.lc_id=this_.id
            ) 
            or (
                nhmcode1_.valid_from is null 
                and sub.validFrom is null
            )
        )
        ...

这反过来导致:

ORA-00904:"SUB _"."VALIDFROM":ungültigerBezeichner

错误消息,表示"无效标识符"

Answer 1

你可以尝试这样的东西,而不是有问题的线:

resultCriterion.add(
  Restrictions.or(
    Restrictions.and(
      Restrictions.isNull("validFrom"),
      Restrictions.sqlRestriction("sub.validFrom is null")
    ),
    Property.forName("validFrom").eq(subselect)
  )
);

这可能不会立即起作用,但希望有所帮助.