Database querry & attempted update not working as expected????

Question

Hi All,
I am posting my question here because it is related to a web application that I am developing. However as this question is database related I may not be posting in the correct location, please forgive me if this is the case.
I recently developed a web application that uses JSP on the front end, servlets for processing, and a mysql database on the back end.
I am using the Tomcat 5 software container, and instead of developing complex database pooling classes I am using the "DataSource" aspect of Tomcat. A relevant section of web.xml follows;
<!-- Database Connection Pool Resources Defined -->
<resource-ref>
      <res-ref-name>jdbc/craftstampindexes</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
</resource-ref>
<resource-ref>
      <res-ref-name>jdbc/stampData</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
</resource-ref>
<resource-ref>
      <res-ref-name>jdbc/craftsurvey</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
</resource-ref>
<resource-ref>
      <res-ref-name>jdbc/currencyconversion</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
</resource-ref>I then access the contents of the databases defined above through a servlet, and then use the results (saved into JavaBeans from the Servlet) to build a JSP.
I have had this code fully functional before. However recently I changed development computers and now the code does not appear to be functional.
When I last had the code functioning information was correctly read from database tables and the tables were also successfully updated (where required).
However now that I have changed development computers, tables are not updating. Strangely enough I am able to querry database tables, however I am not able to update them. Even though my servlet code tries to update the database tables I am not seeing any error messages, all I am seeing is the old contents of the database table, which are not being updated. I thought that I would have seen an error through Tomcat itself if Servlet code failed to update a table, however this is not happening.
The only thing that I can think of which could be contributing to this error is the fact that on my old computer I had mysql installed onto a data patition called "D:\" drive, now I have installed mysql onto the standard Windows root directory "C:\" drive. This doesn't make it any easier for me to understand why tables are being read but not updated!!!
Any help with this will be greatly appreciated, as I am truly at a loss. If I can provide further information which could be of assistance please don't hesitate to let me know.
Thanks for your time.
Kind Regards
David Dartnell

Answer 1

Hi Everyone,
Thanks again for all of your assistance. I have not yet invested the time required to learn Log4j, however I did "lace" my code with println() statements to see what was going on through the console. This is my code as it looks now..
package craftsurvey;
import java.io.*;
import java.sql.*;
import javax.naming.*;
import javax.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class CraftSurveyServlet extends HttpServlet
     private DataSource dataSource;
     public void init(ServletConfig config) throws ServletException
          super.init(config);
          try{
               Context init = new InitialContext();
               Context ctx = (Context) init.lookup("java:comp/env");
               dataSource = (DataSource) ctx.lookup("jdbc/craftsurvey");
               System.out.println("Finished looking up DataSource.");
          }catch (NamingException ex){
               throw new ServletException("Cannot retrieve java:comp/env/jdbc/craftsurvey",ex);
     public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
          doPost(request, response);
     public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
          String surveyVote = request.getParameter("surveybutton");
          System.out.println("Entered doPost() method.");
          String[] finalSurveyResults = new String[5];
          String[] initialSurveyResults = new String[5];
          String newTableValue = "";
          int noOfBears = 0;
          int noOfCountry = 0;
          int noOfFloral = 0;
          int noOfHearts = 0;
          int noOfWording = 0;
          int totalVotes = 0;
          /* Printwriter included for testing purposes */
          response.setContentType("text/html");
          PrintWriter out = response.getWriter();
          Connection con = null;
          Statement stmt = null;
          ResultSet rs1 = null;
          ResultSet rs2 = null; 
          System.out.println("Database access code should be accessed now.");
          /* Database Query performed */
          try {
               synchronized (dataSource) {
                   con = dataSource.getConnection();
               String initialFetch = "SELECT bears, country, floral, hearts, wording FROM survey";           
               stmt = con.createStatement();
               System.out.println("Database Statement created.");
               rs1 = stmt.executeQuery(initialFetch);
               System.out.println("First Database querry performed.");
               while(rs1.next())
                    initialSurveyResults[0] = rs1.getString("bears");
                    initialSurveyResults[1] = rs1.getString("country");
                    initialSurveyResults[2] = rs1.getString("floral");
                    initialSurveyResults[3] = rs1.getString("hearts");
                    initialSurveyResults[4] = rs1.getString("wording");
               noOfBears = Integer.parseInt(initialSurveyResults[0]);
               noOfCountry = Integer.parseInt(initialSurveyResults[1]);
               noOfFloral = Integer.parseInt(initialSurveyResults[2]);
               noOfHearts = Integer.parseInt(initialSurveyResults[3]);
               noOfWording = Integer.parseInt(initialSurveyResults[4]);
               if(surveyVote.equals("bears"))
                    noOfBears++;
                    Integer noOfBearsInt = new Integer(noOfBears);
                    newTableValue = noOfBearsInt.toString();
               else
               if(surveyVote.equals("country"))
                    noOfCountry++;
                    Integer noOfCountryInt = new Integer(noOfCountry);
                    newTableValue = noOfCountryInt.toString();
               else
               if(surveyVote.equals("floral"))
                    noOfFloral++;
                    Integer noOfFloralInt = new Integer(noOfFloral);
                    newTableValue = noOfFloralInt.toString();
               else
               if(surveyVote.equals("hearts"))
                    noOfHearts++;
                    Integer noOfHeartsInt = new Integer(noOfHearts);
                    newTableValue = noOfHeartsInt.toString();
               else
               if(surveyVote.equals("wording"))
                    noOfWording++;
                    Integer noOfWordingInt = new Integer(noOfWording);
                    newTableValue = noOfWordingInt.toString();
               System.out.println("Survey table update about to be attempted.");
               String updateSurvey = "UPDATE survey SET " + surveyVote + "= " + newTableValue;
               stmt.executeUpdate(updateSurvey);
               System.out.println("Survey table updated.");
               String finalFetch = "SELECT bears, country, floral, hearts, wording FROM survey";
               rs2 = stmt.executeQuery(finalFetch);
               System.out.println("Final querry performed.");
               while(rs2.next())
                    finalSurveyResults[0] = rs2.getString("bears");
                    finalSurveyResults[1] = rs2.getString("country");
                    finalSurveyResults[2] = rs2.getString("floral");
                    finalSurveyResults[3] = rs2.getString("hearts");
                    finalSurveyResults[4] = rs2.getString("wording");
             catch(Exception ex)
                 out.println("<H2>Exception Occurred</H2>");
                 out.println(ex);
               if (ex instanceof SQLException)
                    SQLException sqlex = (SQLException) ex;
                    out.println("SQL state: "+sqlex.getSQLState()+"<BR>");
                    out.println("Error code: "+sqlex.getErrorCode()+"<BR>");
             finally{
               try{
                    rs1.close();
                    rs2.close();
               }catch(Exception ex){}                
               try{
                    stmt.close();
               }catch(Exception ex){}
               try{
                    con.close();
               }catch(Exception ex){}
          System.out.println("All table querries should have been performed now.");
          totalVotes = noOfBears + noOfCountry + noOfFloral + noOfHearts + noOfWording;
          SurveyBean surveyResultsBean = new SurveyBean();
          surveyResultsBean.setBearVotes(noOfBears);
          surveyResultsBean.setCountryVotes(noOfCountry);
          surveyResultsBean.setFloralVotes(noOfFloral);
          surveyResultsBean.setHeartVotes(noOfHearts);
          surveyResultsBean.setWordingVotes(noOfWording);
          surveyResultsBean.setTotalVotes(totalVotes);          
          request.setAttribute("surveyResults", surveyResultsBean);
          /* Control forwarded to JSP for display */
          String url = "/ferngully/surveyResults";
          ServletContext servCont = getServletContext();
          RequestDispatcher reqDispatch = servCont.getRequestDispatcher(url);
          System.out.println("Request dispatched to surveyResults.jsp.");
          reqDispatch.forward(request, response);          
}The output I receive at the console as a result of running this code is the following:
Finished looking up DataSource
Entered doPost() method
Database access code should be accessed now
All table querries should have been performed now
Request dispatched to surveyResult.jsp
It looks as though the entire synchronized block of code is being completely skipped!
If anybody could offer further assistance it will be greatly appreciated.
Thanks for your time.
Kind Regards
David