hql

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am getting started with Hibernate and I am using HQL, using some joins to retrieve data from the db but getting this error, any help on how to solve this is appreciated. Field.hbm.xml file: <id name="id" type="string"> <column name="field_map_cd" /> <generator class="assigned"></generator> </id> Rule.hbm.xml file: <many-to-one name="src_field_map" column="field_map_cd" not-null="true" insert="false" update="false"/> <many-to-one name="tgt_field_map" column="field_map_cd" not-null="true" insert="false" update="false"/> HQL query: select t

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I have the following one-to-one relation in Hibernate (that could be null): <one-to-one name="details" class="com.example.Details" lazy="false" cascade="all"/> I am trying to select all entities that have non-null details with HQL: from Entity e where e.details is not null but this returns all entities, no matter whether details are null or not. What would be a correct HQL then? 回答1: Ok I found the solution: select e from Entity e join e.details d where d is not null 回答2: Let's suppose this one-to-one relation is part of the mapping of

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I know this has been asked a lot , but I seem to be having a different problem. I saw that there is a bug in Hibernate that struggles with a SumFunction ignoring custom user types, but I'm not using a custom user type to my knowledge. I'm basically trying to create a new object that is a roll-up of an existing mapping bean, however I receive a NullPointerException against some Hibernate dialect function. I tried using both Double and BigDecimal as my value field type, but both provide me the same error message on deployment. Please help!

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 由 翻译 强力驱动 问题: I'm facing performance issues executing standard spring-data-jpa findAll queries using @NamedEntityGraph When I examine the logs, I see the following statements: 2016 - 10 - 26 09 : 46 : 25 , 681 DEBUG [ http - nio - 8080 - exec - 1 ] CriteriaQueryImpl : Rendered criteria query -> select generatedAlias0 from Patient as generatedAlias0 order by generatedAlias0 . id asc 2016 - 10 - 26 09 : 46 : 25 , 681 DEBUG [ http - nio - 8080 - exec - 1 ] CriteriaQueryImpl : Rendered criteria query -> select count ( generatedAlias0 ) from Patient

以前没怎么用过mybatis，只知道与hibernate一样是个orm数据库框架。随着使用熟练度的增加，发现它与hibernate区别是非常大的，结合至今为止的经验，总结出以下几点： 1.hibernate是全自动，而mybatis是半自动。 hibernate完全可以通过对象关系模型实现对数据库的操作，拥有完整的JavaBean对象与数据库的映射结构来自动生成sql。而mybatis仅有基本的字段映射，对象数据以及对象实际关系仍然需要通过手写sql来实现和管理。 2.hibernate数据库移植性远大于mybatis。 hibernate通过它强大的映射结构和hql语言，大大降低了对象与数据库（oracle、mysql等）的耦合性，而mybatis由于需要手写sql，因此与数据库的耦合性直接取决于程序员写sql的方法，如果sql不具通用性而用了很多某数据库特性的sql语句的话，移植性也会随之降低很多，成本很高。 3.hibernate拥有完整的日志系统，mybatis则欠缺一些。 hibernate日志系统非常健全，涉及广泛，包括：sql记录、关系异常、优化警告、缓存提示、脏数据警告等；而mybatis则除了基本记录功能外，功能薄弱很多。 4.mybatis相比hibernate需要关心很多细节 hibernate配置要比mybatis复杂的多，学习成本也比mybatis高

一、传统的JDBC编程 　　在java开发中，以前都是通过JDBC（Java Data Base Connectivity）与数据库打交道的，至少在ORM（Object Relational Mapping）框架没出现之前是这样，目前常用的ORM框架有JPA、hibernate、mybatis、spring jdbc等，我一开始也是使用JDBC编程，后面开始使用hibernate，有一次开发一个CRM管理系统使用的是Spring JDBC操作数据库，但个人还是不太喜欢这个框架，本人目前使用的最多还是通过mybatis操作数据库，尽管我现在使用的是Spring boot开发，继承了JPA来操作数据库，但是实体类和dao、service、controller层的基本CRUD操作还是通过hibernate代码工具自动生成的，其他操作都是通过mybatis自己编写SQL语句来操作的，因此本文只提JDBC到hibernate再到mybatis的一个过程。 1、什么是JDBC 　　JDBC（Java Data Base Connectivity,java数据库连接）是一种用于执行SQL语句的Java API，是用Java语言编写的类和接口组成的，可以为多种关系型数据库提供统一访问的接口。JDBC提供了一种基准，说白了，也就是sun公司为各大数据库厂商的关系型数据库连接java所制定的规范

How do you pass a list of things for the 'in' clause in Nhibernate HQL? e.g. // data input from the user interface, not known at compile time object[] productIds = {1, 17, 36, ... }; string hqlQuery = @" from Product as prod where prod.Id in ( ? )"; HqlBasedQuery query = new HqlBasedQuery(typeof(Product), hqlQuery, productIds) ActiveRecordMediator.ExecuteQuery(query); Now, this isn't going to work, as much as I wish it would! Am I really stuck doing something like this: // data input from the user interface, not known at compile time object[] productIds = {1, 17, 36, ... }; string hqlQuery = @