title: ResultSet.getString(1) throws java.sql.SQLException: Invalid operation at current cursor position
body: <p>When I run the following servlet:</p>
  
  <pre><code>// package projectcodes;
  public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
      String UserID = request.getParameter("UserID");
      String UserPassword = request.getParameter("UserPassword");
      String userName = null;
      String Email = null;
      Encrypter encrypter = new Encrypter();
      String hashedPassword = null;
      try {
          hashedPassword = encrypter.hashPassword(UserPassword);
          Context context = new InitialContext();
          DataSource ds = (DataSource)context.lookup("java:comp/env/jdbc/photog");
          Connection connection = ds.getConnection();
          String sqlStatement = "SELECT email,firstname FROM registrationinformation WHERE password='" + hashedPassword + "'";
          PreparedStatement statement = connection.prepareStatement(sqlStatement);
          ResultSet set = statement.executeQuery();
          userName = set.getString(1);  // &lt;&lt;---------- Line number 28
          response.sendRedirect("portfolio_one.jsp");
          // userName = set.getString("FirstName");
          Email = set.getString(3);
          if(set.wasNull() || Email.compareTo(UserID) != 0) {
              // turn to the error page
              response.sendRedirect("LoginFailure.jsp");
          } else {
              // start the session and take to his homepage
              HttpSession session = request.getSession();
              session.setAttribute("UserName", userName);
              session.setMaxInactiveInterval(900); // If the request doesn't come withing 900 seconds the server will invalidate the session
              RequestDispatcher rd = request.getRequestDispatcher("portfolio_one.jsp");
              rd.forward(request, response); // forward to the user home-page
          }
      }catch(Exception exc) {
          System.out.println(exc);
      }
  </code></pre>
  
  <p>I get the following exceptions:</p>
  
  <pre><code>INFO: java.sql.SQLException: Invalid operation at current cursor position.
  at org.apache.derby.client.am.SQLExceptionFactory40.getSQLException(Unknown Source)
  at org.apache.derby.client.am.SqlException.getSQLException(Unknown Source)
  at org.apache.derby.client.am.ResultSet.getString(Unknown Source)
  at com.sun.gjc.spi.base.ResultSetWrapper.getString(ResultSetWrapper.java:155)
  
  -----&gt; at projectcodes.ValidateDataForSignIn.doPost(ValidateDataForSignIn.java:28
  
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
  at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1539)
  at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
  at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
  at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
  at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
  at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
  at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
  at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
  at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:330)
  at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
  at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:174)
  at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:828)
  at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:725)
  at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1019)
  at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
  at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
  at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
  at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
  at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
  at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
  at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
  at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
  at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
  at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
  at java.lang.Thread.run(Thread.java:722)
      Caused by: org.apache.derby.client.am.SqlException: Invalid operation at current cursor position.
  at org.apache.derby.client.am.ResultSet.checkForValidCursorPosition(Unknown Source)
  at org.apache.derby.client.am.ResultSet.checkGetterPreconditions(Unknown Source)
  ... 30 more
  </code></pre>
  
  <p>The logs above from the server show that line number 28 is the cause of the exception. But i am unable to get the reason for exception. All the columns in the table have a datatype of varchar.</p>
  
  <p>I have highlighted line number 28 <em>(cause of exception according to server logs)</em> in the servlet code.</p>