误用SQL Server关键字导致的问题

轧钢王子 — Tue, 29 Jan 2008 10:06:00 GMT

刚才在练习��?/span>Hibernate的复合主键例子时�Q�自己很自信的认为已�l�领悟了其中的原理，于是开始制作例子程序。恩�Q�想起前�D�|��间确实有个可以利用复合主键的地方�Q�那��是公寓寝室表，于是开始徏立数据库表：

利用Eclipse自动生成机制�Q�很快就完成了映��文件等的生成，��试一下，却发觉出现错�?br />

1WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
2
3log4j:WARN Please initialize the log4j system properly.
4
5Hibernate: insert into HAIING.dbo.DORMROOM (desc, dorm, room) values (?, ?, ?)
6
7org.hibernate.exception.GenericJDBCException: could not insert: [com.haiing.hibernate.fuhezhujian.DormRoom]
8
9    at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:82)
10
11    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:70)
12
13    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
14
15    at org.hibernate.persister.entity.BasicEntityPersister.insert(BasicEntityPersister.java:1869)
16
17    at org.hibernate.persister.entity.BasicEntityPersister.insert(BasicEntityPersister.java:2200)
18
19    at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:46)
20
21    at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:239)
22
23    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:223)
24
25    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:136)
26
27    at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:274)
28
29    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
30
31    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:730)
32
33    at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:324)
34
35    at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:86)
36
37    at com.haiing.hibernate.fuhezhujian.DormRoomOperate.insert(DormRoomOperate.java:26)
38
39    at com.haiing.hibernate.fuhezhujian.Test2PK.main(Test2PK.java:19)
40
41Caused by: java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]在关键字 'desc' 附近有语法错误�?br /> 42
43    at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source)
44
45    at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
46
47    at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source)
48
49    at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source)
50
51    at com.microsoft.jdbc.sqlserver.tds.TDSRPCRequest.processReplyToken(Unknown Source)
52
53    at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source)
54
55    at com.microsoft.jdbc.sqlserver.SQLServerImplStatement.getNextResultType(Unknown Source)
56
57    at com.microsoft.jdbc.base.BaseStatement.commonTransitionToState(Unknown Source)
58
59    at com.microsoft.jdbc.base.BaseStatement.postImplExecute(Unknown Source)
60
61    at com.microsoft.jdbc.base.BasePreparedStatement.postImplExecute(Unknown Source)
62
63    at com.microsoft.jdbc.base.BaseStatement.commonExecute(Unknown Source)
64
65    at com.microsoft.jdbc.base.BaseStatement.executeUpdateInternal(Unknown Source)
66
67    at com.microsoft.jdbc.base.BasePreparedStatement.executeUpdate(Unknown Source)
68
69    at org.hibernate.jdbc.NonBatchingBatcher.addToBatch(NonBatchingBatcher.java:22)
70
71    at org.hibernate.persister.entity.BasicEntityPersister.insert(BasicEntityPersister.java:1853)
72
73     12 more
74

郁闷了很长时��_��开始以为是主键�c�d��写的hash�c�d��equals�c�L��错误�Q�于是��?/span>org.apache.commons.lang中的对应�Ҏ��重写�Q�可�q�是不行。端详了很长旉��Q�每一�U�可能的错误都考虑了，感觉没啥错误了呀�Q?/span>

又看了一遍错误的代码�Q�发觉已�l�生成了HQL语句�Q�而且错误代码几乎全是数据库的问题。数据库的驱动包我已�l�加�q�来了，而且在其他的例子中运行很正常呀�Q�莫非是提交语句的错误，看了一下看不出什么来�Q�莫非是数据库的问题�Q�去查看表，发觉有点怪怪的�Q?/span>

�q�个desc怎么成介个样子了�Q�莫非设�|�成复合主键之后��成了这个样子，加进一个新的字�D�|��有呀。嘿嘿，那我��删了这个字�D�，在重新加�q�来。结果还是不行！
�q�时我又调整了思�\�Q�把生成�?/span>SQL语句复制到查询分析器中执行，�q�是昄��“在关键字 'desc' 附近有语法错�?/span>”�Q�我晕！看来��是数据库的问题了。等�{�，我突然意识到什么了�Q?/span>

关键字？

desc?

莫非�Q�不是莫非，��是�q�样呀�Q�我怎么忘得一�q�二净了，desc�q�么好的词汇早就被前辈们定义成关键字了，怎么会留�l�我来��用呢�Q?/span>
�Ҏ��desc�Q�一切问题全部解决了�Q�数据成功的插入到数据库之中�Q?/span>

唉，惭愧呀�?/span>

轧钢王子 2008-01-29 18:06 发表评论

在Hibernate中��用oracle的sequence产生主键

轧钢王子 — Wed, 16 Jan 2008 09:49:00 GMT

刚刚接触Hibernate不长旉��Q�今天想动手做一个小例子�Q�数据库使用的是Oracle。打��?span lang="EN-US">Oracle中的序列作�ؓ表的主键�Q�却不知道��?span lang="EN-US">Hibernate如何与其兌��在一赗��请教同事，被告知要使用诸如select语句�q�行查询“select sequence.nextval from dual”�Q�晕倒～

�l�于�{�到中午�Q�上�|�去查资料。得解：
1、在oracle 首先创徏sequence

      create sequence seq_id
      minvalue 1
      start with 1
      increment by 1
      cache 20;

2.在你�?span lang="EN-US">hbm.xml中的配置

     <id column="ID0000" name="id" type="integer">
         <generator class="sequence">
              <param name="sequence">seq_idparam>
         generator>
     id>

�q�样再插入数据的时候，Hibernate回自动生成如下语句：

hibernate: select seq_id.nextval from dual

hibernate: insert into YXJK.T_YXJK_WHRYTXL (XM0000, ZW0000, LXDH00,SJHM00,DZYJ00,IP0000,ID0000) values (?, ?, ?, ?, ?, ?, ?)

自动生成下一个序列��|��然后��对象插入表中�?br /> �q�样问题得解�Q?br />
PS�Q?br /> sequence��是采用数据库提供的sequence机制生成主键。如oralce中的Sequence
native��是�?/span>hibernate�Ҏ��数据库的Dialect�Q�自动采�?/span>identity�Q?/span>hilo�Q?/span>sequence的其中一�U�作��Z��键生成方�?/span>

轧钢王子 2008-01-16 17:49 发表评论

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误用SQL Server关键字导致的问题

在Hibernate中��用oracle的sequence产生主键