ejb访问sqlserver数据库出错。

抛出异常处是：
try {
      makeConnection();
      ResultSet rst = ps.executeQuery("select * from User where userName = 'twoto'");
      while(rst.next()) {
        System.out.println(rst.getString(2));
      }
      System.out.println("User inserted!");
    }
    catch (SQLException ex) {
      ex.printStackTrace();
      throw new UserExistedException(userName);
    }
抛出的异常为;
java.sql.SQLException: 在关键字 'User' 附近有语法错误。 Severity 15, State 1, Pr
ocedure 'LONG null', Line 1
        at weblogic.jdbc.mssqlserver4.TdsStatement.processWarning(TdsStatement.j
ava:1193)
        at weblogic.jdbc.mssqlserver4.TdsStatement.parseMsWarning(TdsStatement.j
ava:1104)
        at weblogic.jdbc.mssqlserver4.TdsStatement.getMoreResults(TdsStatement.j
ava:771)
        at weblogic.jdbc.mssqlserver4.TdsStatement.execute(TdsStatement.java:210
)
        at weblogic.jdbc.mssqlserver4.TdsStatement.executeQuery(TdsStatement.jav
a:54)
        at weblogic.jdbc.wrapper.Statement.executeQuery(Statement.java:316)
        at experiment5.myEJB.UserBean.insertUser(UserBean.java:125)
        at experiment5.myEJB.UserBean.ejbCreate(UserBean.java:36)
        at experiment5.myEJB.User_eecm3e_Impl.ejbCreate(User_eecm3e_Impl.java:19
5)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:324)
        at weblogic.ejb20.manager.DBManager.create(DBManager.java:1139)
        at weblogic.ejb20.manager.DBManager.localCreate(DBManager.java:1118)
        at weblogic.ejb20.internal.EntityEJBLocalHome.create(EntityEJBLocalHome.
java:171)
        at experiment5.myEJB.User_eecm3e_LocalHomeImpl.create(User_eecm3e_LocalH
omeImpl.java:73)
        at experiment5.myEJB.UserManagerBean.register(UserManagerBean.java:43)
        at experiment5.myEJB.UserManager_iq4580_EOImpl.register(UserManager_iq45
80_EOImpl.java:46)
        at experiment5.myEJB.UserManager_iq4580_EOImpl_WLSkel.invoke(Unknown Sou
rce)
        at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:466)
        at weblogic.rmi.cluster.ReplicaAwareServerRef.invoke(ReplicaAwareServerR
ef.java:108)
        at weblogic.rmi.internal.BasicServerRef$1.run(BasicServerRef.java:409)
        at weblogic.security.acl.internal.AuthenticatedSubject.doAs(Authenticate
dSubject.java:353)
        at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:
144)
        at weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.jav
a:404)
        at weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest
.java:30)
        at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
        at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)
experiment5.myException.UserExistedException: UserName : yun has exsited!
        at experiment5.myEJB.UserBean.insertUser(UserBean.java:134)
        at experiment5.myEJB.UserBean.ejbCreate(UserBean.java:36)
        at experiment5.myEJB.User_eecm3e_Impl.ejbCreate(User_eecm3e_Impl.java:19
5)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:324)
        at weblogic.ejb20.manager.DBManager.create(DBManager.java:1139)
        at weblogic.ejb20.manager.DBManager.localCreate(DBManager.java:1118)
        at weblogic.ejb20.internal.EntityEJBLocalHome.create(EntityEJBLocalHome.
java:171)
        at experiment5.myEJB.User_eecm3e_LocalHomeImpl.create(User_eecm3e_LocalH
omeImpl.java:73)
        at experiment5.myEJB.UserManagerBean.register(UserManagerBean.java:43)
        at experiment5.myEJB.UserManager_iq4580_EOImpl.register(UserManager_iq45
80_EOImpl.java:46)
        at experiment5.myEJB.UserManager_iq4580_EOImpl_WLSkel.invoke(Unknown Sou
rce)
        at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:466)
        at weblogic.rmi.cluster.ReplicaAwareServerRef.invoke(ReplicaAwareServerR
ef.java:108)
        at weblogic.rmi.internal.BasicServerRef$1.run(BasicServerRef.java:409)
        at weblogic.security.acl.internal.AuthenticatedSubject.doAs(Authenticate
dSubject.java:353)
        at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:
144)
        at weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.jav
a:404)
        at weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest
.java:30)
        at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
        at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)