JPA本机查询获取单个对象 [英] JPA Native query get a Single Object

问题描述

如何使用JPA本机查询获取单个对象.我做了一些研究，但全部给出的答案是使用"getSingleResult"，但是它没有返回我想要的结果.例如，如果我想获取数据库中的表计数并将其提取到Integer中，该怎么办.

How can i get a single object by using JPA Native query. I did some researches but all give an answer is use "getSingleResult", however it didn't return what i want to get. For example, what should i do if i want to get a count of table in my database and fetch it into a Integer.

下面的代码显示了我如何通过使用Sessison休眠方式来获取此信息:

This code below shows how i get this by using Sessison hibernate:

int check = Integer.parseInt((String) sessionF.createSQLQuery("select to_char(count(*)) as count from user_tables where table_name upper('TEST')").uniqueResult()); 

我希望在JPA中能做到的事

And what i hope to be fine in JPA:

int check = Integer.parseInt((String) getEntityManager().createNativeQuery("select to_char(count(*)) as count from user_tables where table_name upper('TEST')").getSingleResult()); 

很显然，代码没有返回我想要的.因此，请帮助我解决这个问题.谢谢！

Obviously, the code doesn't return what i want. Therefore, please help me to cope with this problem. Thank you !

推荐答案

使用JPA，您需要执行以下操作

With JPA you need to do like following

int num = ((Number)this.entityManager.createNativeQuery("select count(*) from your_table_name")
                .getSingleResult()).intValue();

已

 String name = this.entityManager.createNativeQuery("select t.name from your_table_name t limit 1").getSingleResult().toString();

您将获得num个对象的计数

you will got count with num object

希望它会对您有所帮助.

Hope its will help to you.

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