hibernate派生的属性与XML [英] hibernate derived properties with xml

问题描述

我有名为Student的表格如下

  ID名称DOB 
 --- ----  - ------- 
 1 A 2009-01-28 
 2 B 2001-05-20 
  

我使用派生属性从hbm文件中的dob获取 AGE

 <休眠映射> 
< class name =com.arat.derived.Persontable =personcatalog =spring_db> 
< id name =idtype =int> 
< column name =id/> 
< generator class =assigned/> 
< / id> 
< property name =nametype =string> 
< column name =name/> 
< / property> 
< property name =dobtype =date> 
< column name =doblength =0/> 
< / property> 
  formula =（选择TIMESTAMPDIFF（YEAR，p.dob，NOW（））作为AGE 
从person p where p.ID = ID）>< / property> 
< / class> 
< / hibernate-mapping> 
  

和我的POJO类 Student 具有所有属性id，name，dob和使用setter和getter方法的年龄。

在使用load或get方法获取数据时，我收到错误

  private static void loadPerson（）{
 Session session = factory.openSession（）; 
 Person person =（Person）session.get（Person.class，0）; 
 System.out.println（Person：name+ person.getName（）
 +，dob：+ person.getDob（）+，age：+ person.getAge（）） ; 
 
 
 
 
 
 
  Hibernate：select person0_。 id作为id1_8_0_，person0_.name作为name2_8_0_，person0_.dob作为dob3_8_0_，（作为person0_.AGE从人p处选择TIMESTAMPDIFF（person0_.YEAR，p.dob，NOW（））作为person0_.AGE，其中p.ID = person0_.ID）作为formula0_0_从spring_db.person person0_ where person0_.id =？ 
 Feb 07，2015 7:20:22 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions 
 WARN：SQL错误：1064，SQLState：42000 
 2015年2月7日7： 20:22 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions 
错误：您的SQL语法错误;请检查与您的MySQL服务器版本相对应的手册，以便在第1行中使用'person0_.YEAR，p.dob，NOW（））'作为person0_.AGE（来自人p，其中p.ID = person0_.ID）''） 
 Feb 07，2015 7:20:22 PM org.hibernate.event.internal.DefaultLoadEventListener onLoad 
 INFO：HHH000327：执行加载命令时出错：org.hibernate.exception.SQLGrammarException：无法提取ResultSe * * 
 
 
你能告诉我我错了吗？ 
 
解决方案
这是对RadimKöhler的 https://stackoverflow.com/a/28383566/2576551 回答。似乎自定义方言中的关键字注册对于某些休眠版本是区分大小写的。我正在运行hibernate 4.3.8.Final和关键字必须是小写。 
  //不起作用
 registerKeyword（YEAR）; 
 
 //作品
 registerKeyword（年份）; 
  
相关主题更新到3.6.5后，Hibernate映射的属性到SQL公式失败，提出了小写关键字。  
I have table called Student as Below
ID        NAME     DOB
---       ----     ---------
1         A        2009-01-28
2         B        2001-05-20
I am using derived properties to get the AGE from the dob as below in the hbm file 
<hibernate-mapping>
<class name="com.arat.derived.Person" table="person" catalog="spring_db">
    <id name="id" type="int">
        <column name="id" />
        <generator class="assigned" />
    </id>
    <property name="name" type="string">
        <column name="name" />
    </property>
    <property name="dob" type="date">
        <column name="dob" length="0" />
    </property>
    <property name="age" type="integer" column="AGE"
        formula="( select TIMESTAMPDIFF(YEAR,p.dob,NOW()) as AGE 
                     from person p where p.ID=ID)"></property>
  </class>
</hibernate-mapping>
and my POJO class Student has all the property id,name,dob and age with setter and getter method.

While fetching the data using load or get method I am getting the error
 private static void loadPerson() {
    Session session = factory.openSession();
    Person person = (Person) session.get(Person.class, 0);
    System.out.println("Person : name " + person.getName() 
            + ", dob: " + person.getDob() + ", age : " + person.getAge());

}



  
Hibernate: select person0_.id as id1_8_0_, person0_.name as name2_8_0_, person0_.dob as dob3_8_0_, ( select TIMESTAMPDIFF(person0_.YEAR,p.dob,NOW()) as person0_.AGE from person p where p.ID=person0_.ID) as formula0_0_ from spring_db.person person0_ where person0_.id=?
  Feb 07, 2015 7:20:22 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
  WARN: SQL Error: 1064, SQLState: 42000
  Feb 07, 2015 7:20:22 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
  ERROR: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'person0_.YEAR,p.dob,NOW()) as person0_.AGE from person p where p.ID=person0_.ID)' at line 1
  Feb 07, 2015 7:20:22 PM org.hibernate.event.internal.DefaultLoadEventListener onLoad
  INFO: HHH000327: Error performing load command : org.hibernate.exception.SQLGrammarException: could not extract ResultSe**
can you tell me where I am wrong?
解决方案
This is a small addition to the Radim Köhler's https://stackoverflow.com/a/28383566/2576551 answer. It seems like the keyword registration in a custom dialect is case sensitive for some hibernate versions. I am running hibernate 4.3.8.Final and keyword has to be lowercase. 
//doesn't work
registerKeyword("YEAR");

//works
registerKeyword("year");
Related thread Hibernate mapped property to SQL formula fails after update to 3.6.5 that proposed to lowercase keyword. 

                        
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