SEPARATOR关键字在Hibernate Formula中不能正常工作

问题描述

我有以下的Hibernate forumla query，我可以在mysql workbanch中执行。

I have following Hibernate forumla query, which I am able to execute in mysql workbanch.

select group_concat(distinct t.column_1_name SEPARATOR ', ') from table_name t and t.fk_record_id = record_id

时，column_1_name SEPARATOR'，' ，hibernate将父表附加到SEPRATOR关键字，如下面的查询所示。

While executing this query with Hibernate, hibernate is appending parent table to the SEPRATOR key word as shown in the below query.

select group_concat(distinct t.column_1_name parent_table.SEPARATOR ', ') from table_name t and t.fk_record_id = record_id

这里hibernate没有处理SEPRATOR作为关键字。任何人都有这个想法吗？

Here hibernate is not treating SEPRATOR as keyword. Anyone has any idea about this?

推荐答案

您可以将 SEPARATOR 添加为关键词。实现您自己的 DialectResolver 并将小写字母添加到生成的方言中：

You can add SEPARATOR as keyword. Implement your own DialectResolver and add the keyword in lower case to the resulting dialect:

public class MyDialectResolver extends StandardDialectResolver {

  protected Dialect resolveDialectInternal(DatabaseMetaData metaData) throws SQLException {
    Dialect dialect = super.resolveDialectInternal(metaData);
    dialect.getKeywords().add("separator");
    return dialect;
  }

}

然后你必须告诉Hibernate使用你的方言解析器。例如，在JPA中，您可以在persistence.xml中执行此操作：

You will then have to tell Hibernate to use your dialect resolver. For example in JPA you can do this in your persistence.xml:

<persistence>
  <persistence-unit>
    ...
    <property name="hibernate.dialect_resolvers" value="mypackage.MyDialectResolver"/>
  </persistence-unit>
</persistence>

顺便说一句：同样的情况也适用于其他方言的聚合功能。例如在Oracle中缺少 WITHIN 关键字。

Btw: The same applies to aggregating functions in other dialects. For example in Oracle the WITHIN keyword is missing.

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