I use hibernate + mysql , and configure the entity mapping with "lazy=false" .and deploy my applicaiton.
The first day, all of it worked well,
but since the second day. something exception occured: and stack message is " Could not execute query", and my application dump....

can anybody here help me? many thanks.
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please provide your mappings and stack trace , also the code that does the operation

ok, thanks for your reply, here is my stack messages and the code-related.

org.hibernate.exception.GenericJDBCException: could not execute query
org.hibernate.exception.ErrorCodeConverter.handledNonSpecificException(ErrorCodeConverter.java:92)
org.hibernate.exception.ErrorCodeConverter.convert(ErrorCodeConverter.java:80)
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
org.hibernate.loader.Loader.doList(Loader.java:1596)
org.hibernate.loader.Loader.list(Loader.java:1577)
org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:111)
org.hibernate.impl.SessionImpl.list(SessionImpl.java:1322)
org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:300)
net.mostin.bid.dao.UserDAO.getUserByName(UserDAO.java:52)
net.mostin.bid.action.LoginAction.execute(LoginAction.java:40)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
net.mostin.bid.controll.LoginFilter.doFilter(LoginFilter.java:45)
net.mostin.bid.controll.EncodingFilter.doFilter(EncodingFilter.java:33)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:75)

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and the code is as following.

SystemUser result = null;
Session session = getSession();
try {
Criteria criteria = session.createCriteria(SystemUser.class);
criteria.add(Restrictions.eq("username", username));
Iterator iter = criteria.list().iterator();
if (iter.hasNext()) {
return (SystemUser)iter.next();
}
} finally {
closeSession(session);
}
return result;

i dont think this problem relates to your hibernate code , since it worked the first time . check for any database level errors. maybe u can go through mysql log