通过连接更新值 [英] Update value with join

问题描述

使用Hibernate，我想根据条件更新数据库中的数据，但我得到以下错误：要遍历的节点不能为空

这是我的数据库描述：

 账户：id，email，密码
成员：id，account，team 
团队：id，current（以及对会员=>成员的引用）
  

我的JPA：

  UPDATE Team t SET t.current =：当前LEFT JOIN t.members m WHERE t.current =：current_true AND m.account =：account 
  

我做错了什么？
如果我将LEFT JOIN移到SET之前：

  UPDATE Team t LEFT JOIN t.members m SET t .current =：current WHERE t.current =：current_true AND m.account =：account 
  

我得到了：expect SET，found LEFT

如果我删除了连接：

  UPDATE Team t SET t.current =：current WHERE t.current =：current_true AND t.members.account =：account 
  

我得到了：非法尝试取消引用collection。

更新值的正确方法是什么？

感谢您的帮助！

JPQL中的功能。这是update语句的定义：

这些操作的语法如下：

 update_statement :: = update_clause [where_clause] 
 update_clause :: = UPDATE entity_name [[AS] identification_variable] 
 SET update_item {，update_item} * 
 update_item： ：= [identification_variable。] {state_field | single_valued_object_field} = 
 new_value 
 new_value :: = 
 scalar_expression | 
 simple_entity_expression | 
 NULL 
  

正如您所看到的，这里没有提到对多个实体的支持。我想你必须找到一种不同的方式来做到这一点，也许创建一个方法来选择你想要先更新的实体，然后迭代设置值的结果。或者您可以使用本地SQL更新。

using Hibernate, I'd like to update a data in the database based on conditions, but I got the following error : "node to traverse cannot be null"

Here is my database description :

Account: id, email, password
Member : id, account, team
Team: id, current (and a reference to member => members)

Here is my JPA :

UPDATE Team t SET t.current = :current LEFT JOIN t.members m WHERE t.current = :current_true AND m.account = :account

What am I doing wrong? If i move the LEFT JOIN to before the SET :

UPDATE Team t LEFT JOIN t.members m SET t.current = :current WHERE t.current = :current_true AND m.account = :account

I got : "expecting SET, found LEFT"

If I remove the join :

UPDATE Team t SET t.current = :current WHERE t.current = :current_true AND t.members.account = :account

I got : "Illegal attempt to dereference collection".

What is the correct way to update values ?

Thanks for your help!

解决方案

The JPA 2.0 specification in chapter 4 contains details of all supported features in JPQL. This is the definition of the "update" statement:

The syntax of these operations is as follows:

update_statement ::= update_clause [where_clause]
 update_clause ::= UPDATE entity_name [[AS] identification_variable] 
                     SET update_item {, update_item}*
  update_item ::= [identification_variable.]{state_field | single_valued_object_field} =
                     new_value 
new_value ::= 
   scalar_expression |
   simple_entity_expression |
   NULL

As you can see, support for multiple entities is not stated here. I guess you will have to find a different way to do it, perhaps create a method that selects the entities that you want to update first, and then iterate over the results setting the values. Or you could use a native SQL update.

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