hibernate 中为什么一进行数据库操作就有这些警告错误，如何解决。

详细DEBUG信息如下：
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2006-05-31 11:13:23,093 DEBUG ConnectionManager - closing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets: 0, globally: 0)]
2006-05-31 11:13:23,125 DEBUG JDBCExceptionReporter - SQL Warning
java.sql.SQLWarning: [Microsoft][SQLServer 2000 Driver for JDBC]Database changed to test
at com.microsoft.jdbc.base.BaseWarnings.createSQLWarning(Unknown Source)
at com.microsoft.jdbc.base.BaseWarnings.get(Unknown Source)
at com.microsoft.jdbc.base.BaseConnection.getWarnings(Unknown Source)
at org.hibernate.util.JDBCExceptionReporter.logAndClearWarnings(JDBCExceptionReporter.java:22)
at org.hibernate.jdbc.ConnectionManager.closeConnection(ConnectionManager.java:325)
at org.hibernate.jdbc.ConnectionManager.cleanup(ConnectionManager.java:262)
at org.hibernate.jdbc.ConnectionManager.close(ConnectionManager.java:194)
at org.hibernate.impl.SessionImpl.close(SessionImpl.java:289)
at com.medlink.hibernate.HibernateSessionFactory.closeSession(HibernateSessionFactory.java:73)
at com.medlink.struts.form.AddAdminForm.validate(AddAdminForm.java:77)
at org.apache.struts.action.RequestProcessor.processValidate(RequestProcessor.java:928)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:204)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.medlink.sys.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:36)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:868)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:663)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)
2006-05-31 11:13:23,546 WARN  JDBCExceptionReporter - SQL Warning: 0, SQLState: 
2006-05-31 11:13:23,546 WARN  JDBCExceptionReporter - [Microsoft][SQLServer 2000 Driver for JDBC]Database changed to test
2006-05-31 11:13:23,562 WARN  JDBCExceptionReporter - SQL Warning: 0, SQLState: 
2006-05-31 11:13:23,578 WARN  JDBCExceptionReporter - [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]Changed database context to 'test'.
2006-05-31 11:13:23,609 WARN  JDBCExceptionReporter - SQL Warning: 0, SQLState: 
2006-05-31 11:13:23,609 WARN  JDBCExceptionReporter - [Microsoft][SQLServer 2000 Driver for JDBC]Language changed to us_english
2006-05-31 11:13:23,625 WARN  JDBCExceptionReporter - SQL Warning: 0, SQLState: 
2006-05-31 11:13:23,640 WARN  JDBCExceptionReporter - [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]Changed language setting to us_english.
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