使用JPA和Hibernate时DISTINCT如何工作 [英] How does DISTINCT work when using JPA and Hibernate

问题描述

DISTINCT在JPA中使用哪一列，是否可以对其进行更改?

What column does DISTINCT work with in JPA and is it possible to change it?

以下是使用DISTINCT的示例JPA查询:

Here's an example JPA query using DISTINCT:

select DISTINCT c from Customer c

这没有什么意义-区别基于哪个列?是否在Entity上将其指定为注释，因为找不到?

Which doesn't make a lot of sense - what column is the distinct based on? Is it specified on the Entity as an annotation because I couldn't find one?

我想指定进行区分的列，例如:

I would like to specify the column to make the distinction on, something like:

select DISTINCT(c.name) c from Customer c

我正在使用MySQL和Hibernate.

I'm using MySQL and Hibernate.

推荐答案

更新:请参阅投票最多的答案.

我自己的已过时.仅出于历史原因才保留在这里.

在Joins中通常需要在HQL中有区别，而在像您自己这样的简单示例中则不需要.

Distinct in HQL is usually needed in Joins and not in simple examples like your own.

另请参见如何在HQL中创建独立查询

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