java - 未使用 Hibernate 标准投影别名

Question

Hibernate Projection 别名是否有效？我可以发誓它只是没有。至少，它没有按照我的预期去做。

这是Java:

return sessionFactory.getCurrentSession()
    .createCriteria(PersonProgramActivity.class)
    .setProjection(Projections.projectionList()
        .add(Projections.alias(Projections.sum("numberOfPoints"), "number_of_points"))
        .add(Projections.groupProperty("person.id")))
    .setFirstResult(start)
    .setFetchSize(size)
    .addOrder(Order.desc("numberOfPoints"))
    .list();

这是它生成的 SQL:

select
    sum(this_.number_of_points) as y0_,
    this_.person_id as y1_
from
    PERSON_PROGRAM_ACTIVITY this_
group by
    this_.person_id
order by
    this_.number_of_points desc

它似乎根本没有使用别名。我认为设置别名意味着 sum(this_.number_of_points) 将被别名为 number_of_points 而不是 y0_。有什么我想念的技巧吗？

谢谢。

Answer 1

您需要为整个条件指定一个别名，然后您可以创建实际使用的其他别名。奇怪的是别名变成了 y0_ 而不是相反。

return sessionFactory.getCurrentSession()
    .createCriteria(PersonProgramActivity.class, "ppa")
    .setProjection(Projections.projectionList()
        .add(Projections.alias(Projections.sum("numberOfPoints"), "ppa.numberOfPoints"))
        .add(Projections.groupProperty("person.id")))
    .setFirstResult(start)
    .setFetchSize(size)
    .addOrder(Order.desc("ppa.numberOfPoints"))
    .list();

生成以下 SQL:

select
    sum(this_.number_of_points) as y0_,
    this_.person_id as y1_
from
    PERSON_PROGRAM_ACTIVITY this_
group by
    this_.person_id
order by
    this_.y0_ desc