HQL：通过加入选择总和组

Question

在 HQL 中，我会进行这样的查询：
我想按类别选择类别名称和总和 montantdebit

category{ idcategory ;namecategory}  

和

 operation {montantdebit , Category}

我尝试了以下方法：

select cat.nameCategory, sum(operation.montantdebit)  from Operation operation join  operation.category  cat group  by cat.idCategory

我遇到了错误：

Caused by: org.springframework.dao.InvalidDataAccessResourceUsageException: could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:242) ~[spring-orm-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:225) ~[spring-orm-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:527) ~[spring-orm-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61) ~[spring-tx-5.0.5.RELEASE.jar:5.0.5.RELEASE]

Answer 1

• 您能否提供更多详细信息，例如表的数量和列中的列？ 表。

• 或者你可以参考下面给出的查询：

  Query query = session.createQuery("from Employee");

  query = session.createQuery("select e.name, sum(e.salary), 计数(e)" + " from Employee e where e.name like '%i%' group by e.name");

• 或者您可以参考以下来源： https://www.journaldev.com/2954/hibernate-query-language-hql-example-tutorial

Answer 2

在您的查询中需要修复两件事：

1. 您必须在GROUP BY 子句中包含字段名称类别
2. 您可以排除JOIN 子句，因为Category 对象是封装在Operation 对象中的对象

您必须按如下方式编写查询：

SELECT operation.category.nameCategory, sum(operation.montantdebit) 
FROM Operation operation
GROUP BY operation.category.idCategory, operation.category.nameCategory