更好的方法是:JPA的getSingleResult或getResultList [英] what is better: getSingleResult, or getResultList JPA

问题描述

我需要从表中检索单个行，并且我对哪种方法更好感兴趣. 一方面，getSingleResult设计用于检索单个结果，但是会引发异常.此方法是否对与getResultList和

i need to retrieve single row from table, and i was interested what approach is better. On the one side getSingleResult is designed for retrieving single result, but it raises exception. Does this method have benefit in performance related to getResultList with

query.setFirstResult(0);
query.setMaxResults(1); 

推荐答案

getSingleResult如果存在多行，则抛出NonUniqueResultException.它旨在在真正存在单个结果时检索单个结果.

getSingleResult throws NonUniqueResultException, if there are multiple rows. It is designed to retrieve single result when there is truly a single result.

您的工作方式很好，并且JPA可以正确处理此问题.同时，您无法将它与getSingleResult进行任何比较，因为它无法正常工作.

The way you did is fine and JPA is designed to handle this properly. At the same time, you cannot compare it against getSingleResult any way, since it won't work.

但是，根据您正在使用的代码，始终最好对查询进行细化以返回单个结果，如果这就是您想要的全部，那么只需调用getSingleResult.

However, depend on the code you are working on, it is always better to refine the query to return single result, if that's all what you want - then you can just call getSingleResult.

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