休眠条件子查询

Hibernate Criteria Subquery(休眠条件子查询)

问题描述

我需要使用 detachedCriteria 执行此 SQL 查询:

I need to do this SQL query with detachedCriteria:

SELECT g.id FROM games g
WHERE NOT EXISTS (
    SELECT 1 FROM users_games ug WHERE ug.user_id = 1 AND g.id = ug.game_id)

我们的想法是从不属于用户的游戏中获取 ID.我用 detachedCriteria 尝试了 10 种不同的方法，但我得到了未知实体:null"MappingException代码应如下所示:

The idea is to get the ids from the games that aren't owned by the user. I tried like 10 different approaches with detachedCriteria but I get the "Unknown entity: null" MappingException The code should look like:

DetachedCriteria subquery = DetachedCriteria.forClass(UserGame.class, "ug")
   .add(Restrictions.eq("ug.user.id", 1))
   .add(Restrictions.eqProperty("ug.game.id","u.id"));
DetachedCriteria criteria = DetachedCriteria.forClass(Game.class, "g")
   .add(Subqueries.notExists(subquery));

还将预测设置为仅返回游戏的 id.

Setting also the projections to return only the id of the games.

有什么想法吗?我认为 Hibernate 在加入没有别名的查询时遇到了一些麻烦.添加别名有效，但结果非常错误.

Any ideas? I think Hibernate has some trouble joining the queries with no alias. Adding alias works but the results are quite wrong.

推荐答案

需要添加别名，如下:

DetachedCriteria subquery = DetachedCriteria.forClass(UserGame.class, "ug")
   .addAlias("ug.user", "user")
   .add(Restrictions.eq("user.id", 1))
   .addAlias("ug.game", "game")
   .add(Restrictions.eqProperty("game.id","u.id"));

应该有帮助

这篇关于休眠条件子查询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！