前一段时间在做一个项目时，遇到同样的代码在连接oracle的时候正常，在连接DB2数据库的时候出现异常不说，后台哗哗的报错.......直接上图吧：
[myProject] ERROR 2012-08-08 17:41:31,921 method:org.hibernate.util.JDBCExceptionReporter.logExceptions(JDBCExceptionReporter.java:72)
DB2 SQL error: SQLCODE: -104, SQLSTATE: 42601, SQLERRMC: );(+;(
[myProject] WARN 2012-08-08 17:41:31,921 method:org.hibernate.util.JDBCExceptionReporter.logExceptions(JDBCExceptionReporter.java:71)
SQL Error: -727, SQLState: 56098
[myProject] ERROR 2012-08-08 17:41:31,921 method:org.hibernate.util.JDBCExceptionReporter.logExceptions(JDBCExceptionReporter.java:72)
DB2 SQL error: SQLCODE: -727, SQLSTATE: 56098, SQLERRMC: 2;-104;42601;)|(+|(
[myProject] WARN 2012-08-08 17:41:31,921 method:org.hibernate.util.JDBCExceptionReporter.logExceptions(JDBCExceptionReporter.java:71)
SQL Error: -727, SQLState: 56098
[myProject] ERROR 2012-08-08 17:41:31,921 method:org.hibernate.util.JDBCExceptionReporter.logExceptions(JDBCExceptionReporter.java:72)
DB2 SQL error: SQLCODE: -727, SQLSTATE: 56098, SQLERRMC: 2;-104;42601;)|(+|(
org.hibernate.exception.GenericJDBCException: could not load an entity: [cn.test.oais.driver.database.EssTag#23111]
at org.hibernate.exception.ErrorCodeConverter.handledNonSpecificException(ErrorCodeConverter.java:92)
at org.hibernate.exception.ErrorCodeConverter.convert(ErrorCodeConverter.java:80)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1359)
at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:116)
at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:101)
at org.hibernate.loader.entity.BatchingEntityLoader.load(BatchingEntityLoader.java:82)
at org.hibernate.persister.entity.BasicEntityPersister.load(BasicEntityPersister.java:2471)
at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:351)
at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:332)
at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:113)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:151)[
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:79)
at org.hibernate.impl.SessionImpl.load(SessionImpl.java:603)
at org.hibernate.impl.SessionImpl.load(SessionImpl.java:596)
at cn.keyoflov.oais.driver._BaseRootDAO.load(_BaseRootDAO.java:744)
at cn.test.oais.driver.database.impl.StructureDefineService.getEssTag(StructureDefineService.java:1288)
at cn.test.oais.driver.database.impl.StructureDefineService.setTag(StructureDefineService.java:1644)
at cn.test.oais.ipe.metadata.Tag.setTag(Tag.java:163)
at cn.test.oais.webapp.action.manage.metadata.StructureAction.editTags(StructureAction.java:4257)
at cn.test.oais.webapp.action.manage.metadata.StructureAction.saveGridData(StructureAction.java:4585)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:276)
at cn.test.oais.webapp.struts.BaseAction._execute(BaseAction.java:181)
at cn.test.oais.webapp.struts.BaseAction.execute(BaseAction.java:155)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421)
at cn.test.oais.webapp.struts.RequestDynamicProcessor.process(RequestDynamicProcessor.java:114)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:415)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.test.oais.webapp.filter.ActionFilter.doFilter(ActionFilter.java:88)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:323)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.test.oais.webapp.filter.GZIPFilter.doFilter(GZIPFilter.java:49)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.displaytag.filter.ResponseOverrideFilter.doFilter(ResponseOverrideFilter.java:125)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:75)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.opensymphony.clickstream.ClickstreamFilter.doFilter(ClickstreamFilter.java:42)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:174)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:292)
at org.acegisecurity.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:108)
at org.acegisecurity.intercept.web.SecurityEnforcementFilter.doFilter(SecurityEnforcementFilter.java:197)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:303)
at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:143)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:303)
at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:154)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:303)
at org.acegisecurity.wrapper.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:50)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:303)
at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:246)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:303)
at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:220)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:303)
at org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:173)
at org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:120)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.test.oais.webapp.filter.SessionTimeoutFilter.doFilter(SessionTimeoutFilter.java:45)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:595)
Caused by: com.ibm.db2.jcc.c.SqlException: DB2 SQL error: SQLCODE: -104, SQLSTATE: 42601, SQLERRMC: );(+;(
at com.ibm.db2.jcc.c.tf.e(tf.java:1680)
at com.ibm.db2.jcc.c.tf.a(tf.java:1239)
at com.ibm.db2.jcc.b.jb.h(jb.java:139)
at com.ibm.db2.jcc.b.jb.a(jb.java:43)
at com.ibm.db2.jcc.b.w.a(w.java:30)
at com.ibm.db2.jcc.b.cc.f(cc.java:161)
at com.ibm.db2.jcc.c.tf.n(tf.java:1219)
at com.ibm.db2.jcc.c.uf.gb(uf.java:1816)
at com.ibm.db2.jcc.c.uf.d(uf.java:2298)
at com.ibm.db2.jcc.c.uf.X(uf.java:508)
at com.ibm.db2.jcc.c.uf.executeQuery(uf.java:491)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:120)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1272)
at org.hibernate.loader.Loader.doQuery(Loader.java:391)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:218)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1345)
... 86 more
查看报错的方法，发现里面代码是
private EssTag getEssTag(EssStructure es, Field identifier, Session session)
throws Exception {
return (EssTag) this.load(EssTag.class, this.getTagId(es, identifier,session), session);
}
而报错的代码就是this.load(EssTag.class, this.getTagId(es, identifier,session), session)这一句.....
然后看一下我从网上查到的关于这个异常的解释
org.hibernate.exception.GenericJDBCException: could not load an entity
（解释一下this.getTagId(es, identifier,session)取出来的就是一个long数据，值为23111。）
有说是：
1.普遍的人都会想到的，也就是大多数说的比较浅显的就是说没有主键=23111的这条记录
于是找到EssTag.hbm.xml，找到其映射表名ess_tag，在PL/SQL
下select * from ess_tag where id=23111 ，确实存在这个记录，这个因素可以排除。
2.有说是JDBC驱动的问题，问题是驱动包版本过低，说换一个jar包问题迎刃而解，我不信，但还是查看了jar包版本，发现是最新的jar包。当然这其中也有说是hibernate的jar包的问题的，我更不信，况且如果是jar包的问题的话，
oracle10G下可以正常跑程序啊，到了DB2数据库hibernate的jar包就不好使了，这个理由太扯了......
下面关注这个异常
Caused by: com.ibm.db2.jcc.c.SqlException: DB2 SQL error: SQLCODE: -104, SQLSTATE: 42601, SQLERRMC: );(+;(
参照http://www.ufaith.cn/read-65.html这个博客里面的关于DB2各代码的解释，不难看出是说sql有问题.....那么我就奇怪了，这明明就是利用hibernate的机制，直接load数据，传一个实体xx.class，数据主键id,session，就可以加载该条数据
（注意：前提是存在这个实体xx的映射文件，而且xx的映射文件一定要被装载，
在我的项目中是有EssTag.java，有EssTag.hbm.xml，而且applicationContext-resources.xml里面已经装载了映射文件。）
不过我还是比较相信确实sql有问题，于是在spring配置文件applicationContext-resources.xml里面将
<!-- 输出所有SQL语句到控制台.取值 true | false -->
<prop key="hibernate.show_sql">false</prop>
这一项的值改为true，于是所有的hql全都打印在控制台了，翻译成sql之后，把sql语句粘到oracle 的PL/SQL窗口可以顺利执行，粘到DB2的sql执行窗口，果然执行不了..........
读者请理解一下这里.....我就不将我的真实sql粘过来了.........
可以告诉大家的是，那个sql是很长的，使用的外连接，就是那种很传统的外连接写法，使用“(+)”来表示的那种，之前有听过说8i以下的版本不支持使用LEFT/RIGHT/FULL OUTER JOIN这种的外连接写法，因为使LEFT/RIGHT/FULL OUTER JOIN这种的外连接写法是比较高级的语法，而8i以下版本过低，解析不了这么高级的语法.......当然这是题外话，目的是想说这个sql在目前的oracle中（无论版本高低）是完全不可能出问题的......
注意到这个报错信息SQLERRMC: );(+;(，注意到那几个奇怪的括号，于是我也是猜想，这个sql里面就外连接那里出现(+)，难道是这个外连接导致的......于是把(+)这种的外连接翻译成LEFT OUTER JOIN 的这种写法，放到DB2中去执行，可以顺利执行......
于是真相渐渐渐渐浮出水面，答案越来越清晰了.......
DB2数据库不支持(+)这种的外连接的写法，支持LEFT OUTER JOIN 这种的外连接写法，但目前我还不太确信是不是所有DB2版本都不支持，我所知道的是8.x和9.X的版本目前都不支持(+)这种的外连接写法.......
读者不防自己尝试一下：
1. LEFT OUTER JOIN：左外关联
SELECT e.last_name, e.department_id, d.department_name
FROM employees e
LEFT OUTER JOIN departments d
ON (e.department_id = d.department_id);
（这种语法在DB2下能执行成功）
等价于
SELECT e.last_name, e.department_id, d.department_name
FROM employees e, departments d
WHERE e.department_id=d.department_id(+);
（这种语法在DB2下不能执行成功）
结果为：所有员工及对应部门的记录，包括没有对应部门编号department_id的员工记录。
2. RIGHT OUTER JOIN：右外关联
SELECT e.last_name, e.department_id, d.department_name
FROM employees e
RIGHT OUTER JOIN departments d
ON (e.department_id = d.department_id);
（这种语法在DB2下能执行成功）
等价于
SELECT e.last_name, e.department_id, d.department_name
FROM employees e, departments d
WHERE e.department_id(+)=d.department_id;
（这种语法在DB2下不能执行成功）
结果为：所有员工及对应部门的记录，包括没有任何员工的部门记录。
但是又出现了一个比较纠结的问题，代码里面用的是hibernate的load...直接传的xx.class,id,session，那一堆hql是它自己内部拼出来的啊，我怎么样去改变它拼hql的语法啊，苦恼啊 ，苦恼....无尽的痛苦.......我遇到问题总是会自己先纠结上一阵的，自己能办到的事，坚决不求别人.....无奈之下，请教了一个DB2数据库高手吧.......
我把我的研究成果告诉了他，他也确认了确实是外连接语法不正确导致的，他告诉我一个配置文件里面可以配置DB2外连接的语法，是使用left outer join ，还是(+).....
但是他也不记得在哪个配置文件里面配置的了............于是我又开始苦恼啊 ，苦恼...................................................................................
后来我发现是在applicationContext-resources.xml里面有个
<prop key="hibernate.dialect">org.hibernate.dialect.OracleDialect</prop>
这一句改成org.hibernate.dialect.DB2Dialect，于是重启服务以后，打印的hql果真不再使用(+)这种外连接了，使用正规的left outer join...... 控制台也不再报那两种奇怪的异常了....这说明定义hibernate的方言搞错了，于是hibernate翻译的hql造成了错误.........
我的问题OK了！.不用改一行代码..........
这个博客里面又比较详细的外连接语法的解释和举例：
http://anjian0802.blog.163.com/blog/static/47988453201031803577/