No Dialect mapping for JDBC type 错误分析

当在hibernate中运用原始的sql语句进行操作的的时候，常常会报错，错误很多都是关于 
No Dialect mapping for JDBC type类型的错误，经过分析和查找，问题常常发生在几个地方 
1、错误的配置了hibernate的方言 
2、就是你的数据库中的字段和java里面的类型不匹配的问题 
具体信息如： 
eg： 
Session session = HibernateSessionFactory.getSession(); 
String sql = "SELECT Daymarketinfo.* FROM (select * from daymarketinfo d order by market_time desc ) as Daymarketinfo group by contract_id;"; 
Query query = session.createSQLQuery(sql); 
List<?> list = query.list();//错误出现位置 
List<JsonData> jsonList = new ArrayList<JsonData>(); 
for (Object obj : list) { 
  Object[] arr = (Object[])obj; 
  JsonData oJson = new JsonData(); 
  oJson.setId((Integer)arr[0]); 
  /* 
    对arr数组取出一个个取出相应的数据就可以了，在这里就不多赘述 
  */ 
jsonList.add(dk); 
} 
request.setAttribute("jsonList", jsonList); 
return mapping.findForward("success"); 

错误信息如下： 

org.hibernate.MappingException: No Dialect mapping for JDBC type: 7 
at org.hibernate.dialect.TypeNames.get(TypeNames.java:56) 
at org.hibernate.dialect.TypeNames.get(TypeNames.java:81) 
at org.hibernate.dialect.Dialect.getHibernateTypeName(Dialect.java:192) 
at org.hibernate.loader.custom.CustomLoader.getHibernateType(CustomLoader.java:161) 
at org.hibernate.loader.custom.CustomLoader.autoDiscoverTypes(CustomLoader.java:131) 
at org.hibernate.loader.Loader.getResultSet(Loader.java:1678) 
at org.hibernate.loader.Loader.doQuery(Loader.java:662) 
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224) 
at org.hibernate.loader.Loader.doList(Loader.java:2145) 
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2029) 
at org.hibernate.loader.Loader.list(Loader.java:2024) 
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:111) 
at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1655) 
at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142) 
at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:164) 
at com.futures.action.manage.DaymarketinfoAction.execute(DaymarketinfoAction.java:57) 
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419) 
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224) 
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194) 
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
at filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:105) 
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:175) 
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:263) 
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) 
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584) 
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) 
at java.lang.Thread.run(Unknown Source) 


解决方法为：通过查询hibernate的源码，找到问题的根本所在，就是hibernate中不支持对应的数据类型，具体数据类型的值，请查看下表 


查看 java.sql.Types 类，可以找到对应类型，调整相应的数据库里的类型，或者其他支持这个类型的方言。