Java 无法正确获取查询结果

我已经编写了以下

查询

select 
  count (distinct asset.assetId) 
from 
  Asset asset 
  left join asset.assetTitles title  
  left join asset.distTypes distTypes
where 
  title.program.id in (:progIdParam) 
  and distTypes in (:lkpDistTypeId) 
  and asset.active = 1
  and asset.isShow = 1
  and asset.classification = 'Internal Use'

我称之为：

 private Long assetTitleListForIp = 0L;

 assetTitleListForIp = (Long)entityManager
      .createQuery(query)                                 
      .setParameter("progIdParam",progId)
      .setParameter("lkpDistTypeId",LookupValueEnum.DIST_TYPE_INTL_PRODUCTION.getLkpId())
      .getSingleResult();

---

如果我在eclipse控制台中启动查询并在DB中运行它，它将count显示为1。但在应用程序中，对于assetTitleListForIp，它将值赋值为零。我没有犯我所犯的小错误。有人能帮忙吗？

可能你的铸造有问题

getSingleResult（）

不会直接强制转换为

Long

。尝试得到如下结果：

Object countObj=entityManager.createQuery(
               "select count (distinct asset.assetId) from Asset asset left join "+
               "asset.assetTitles title  left join asset.distTypes distTypes where "+
               "title.program.id in (:progIdParam) and distTypes in (:lkpDistTypeId) "+
               "and asset.active =1 and asset.isShow = 1 and asset.classification "+
               "='Internal Use'")
               .setParameter("progIdParam",progId)
               .setParameter("lkpDistTypeId",
               LookupValueEnum.DIST_TYPE_INTL_PRODUCTION.getLkpId())
               .getSingleResult();

Long count=Long.valueOf(""+countObj);
assetTitleListForIp=count;

---

看起来像是

assetTitleListForIp

是字段。我怀疑你的问题与查询本身无关。可能的问题：

• 查询以all方式运行，您看到的只是

  assetTitleListForIp

• assetTitleListForIp

  在执行查询的方法中被局部变量屏蔽
• 您正在从保存该字段的对象的某个其他实例读取该字段

  assettilelistforip