HQL/JPQL - 在FROM上嵌套选择

Question

我尝试将我的SQL查询转换为HQL或JPQL(我希望受益于对象映射).

我的SQL请求是:

SELECT * 
FROM (SELECT bde, MAX(creation_date) 
      FROM push_campaign GROUP BY bde) temp, 
push_campaign pc where pc.bde = temp.bde and pc.creation_date = temp.creation_date;

我尝试(不成功)在JPQL中转换它:

select pc 
from (select bde, max(creationDate) 
      from PushCampaign group by bde) temp, 
PushCampaign pc 
where pc.bde = temp.bde and pc.creationDate = temp.creationDate

但我得到了提升:

IllegalArgumentException occured :

org.hibernate.hql.ast.QuerySyntaxException:意外令牌:(第1行,第16列[选择pc from(select id,max(creationDate)from models.PushCampaign group by bde)temp,models.PushCampaign pc where pc.id = temp.id]

我读的嵌套选择只能在select或where子句中.

您是否有解决方案来保持对象映射的请求和好处？

Answer 1

不可能在单个请求中使用 JPQL 或 HQL。

为了在一个请求中做到这一点，我建议这样做：

String campaignToLaunch = "select pc.* from PushCampaign pc ..."
//SQL request which return a resultset compatible with the models.PushCampaign class
Class className = Class.forName("models.PushCampaign");
List<PushCampaign> result = JPA.em()
                           .createNativeQuery(campaignToLaunch,className)
                           .getResultList();