update problem in oracle

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import oracle.sql.*;
import oracle.jdbc.*;
 
public class Update extends HttpServlet
{
 public void service(HttpServletRequest req,HttpServletResponse res)
 throws ServletException,IOException
 {
 PrintWriter out = res.getWriter();
 System.out.println("1");
 String s1 = req.getParameter("phone");
 System.out.println(s1);
 String s2 = req.getParameter("email");
 System.out.println(s2);
 String s3 = req.getParameter("qual");
 System.out.println(s3);
 String s4 = req.getParameter("ss");
 System.out.println(s4);
 String s5 = req.getParameter("cn");
 System.out.println(s5);
 String s6 = req.getParameter("ds");
 System.out.println(s6);
 String s7 = req.getParameter("exp");
 System.out.println(s7);
 String s8 = req.getParameter("sal");
 System.out.println(s8);
 String s9 = req.getParameter("lc");
 System.out.println(s9);
 String s10 = req.getParameter("dsf");
 System.out.println(s10);
 String s11 = req.getParameter("es");
 System.out.println(s11);
 String s12 = req.getParameter("so");
 System.out.println(s12);
 String s13 = req.getParameter("rst");
 System.out.println(s13);
 String s14 = req.getParameter("id");
 System.out.println(s14);
 String s15 = req.getParameter("cts");
 System.out.println(s15);
 String s16 = req.getParameter("Id");
 System.out.println(s16);
 String s17 = req.getParameter("First_Name");
 System.out.println(s17);
 String s18 = req.getParameter("Last_Name");
 System.out.println(s18);
 String s19 = req.getParameter("Date_Of_Birth");
 System.out.println(s19);
 System.out.println("2");
 try
 {
 Class.forName("oracle.jdbc.driver.OracleDriver");
 Connection con = DriverManager.getConnection("jdbc :-o	 racle:thin:@10.11.32.86:1521:Resumedb","scott","tiger");
 Statement stmt = con.createStatement();
 System.out.println("3");
 String sql = "update candidates set Phone='"+s1+"',Email='"+s2+"',Qualification='"+s3+"',Skill_Set='"+s4+"',Company='"+s5
+"',Designation='"+s6+"',Experience="+s7+",Salary="+s8+",Location='"+s9+"',Designation_Applied_For='"
+s10+"',Expected_Salary="+s11+",Salary_Offered="+s12+",Result='"+s13
+"',Interview_Date=to_date('"+s14+"','DD-MM-YYYY'),Comments='"+s15+"' where Id="+s16+"";
 // String sql = "update candidates set Phone='"+s1+"' where Id="+s16+"";
 // String sql1 = "update candidates set Email='"+s2+"' where Id="+s16+"";
 //String sql2 = "update candidates set Qualification='"+s3+"' where Id="+s16+"";
 //String sql3 = "update candidates set Skill_Set='"+s4+"' where Id="+s16+"";
 //String sql4 = "update candidates set Company='"+s5+"' where Id="+s16+"";
 //String sql5 = "update candidates set Designation='"+s6+"' where Id="+s16+"";
 //String sql6 = "update candidates set Experience="+s7+" where Id="+s16+"";
 //String sql7 = "update candidates set Salary="+s8+" where Id="+s16+"";
 //String sql8 = "update candidates set Location='"+s9+"' where Id="+s16+"";
 //String sql9 = "update candidates set Designation_Applied_For='"+s10+"' where Id="+s16+"";
 //String sql10 = "update candidates set Expected_Salary="+s11+" where Id="+s16+"";
 //String sql11 = "update candidates set Salary_Offered="+s12+" where Id="+s16+"";
 //String sql12 = "update candidates set Result='"+s13+"' where Id="+s16+"";
 //String sql13 = "update candidates set Interview_Date=to_date('"+s14+"','DD-MM-YYYY') where Id="+s16+"";
 //String sql14 = "update candidates set Comments='"+s15+"' where Id="+s16+"";
 
 //String sql = "update candidates set Phone='08812 241749' where first_name='Giri'";
 System.out.println("4");
 stmt.execute(sql);
 System.out.println("ex1");
 //stmt.execute(sql1);
 //System.out.println("ex2");
 //stmt.execute(sql2);
 //System.out.println("ex3");
 //stmt.execute(sql3);
 //System.out.println("ex4");
 //stmt.execute(sql4);
 //System.out.println("ex5");
 //stmt.execute(sql5);
 //System.out.println("ex6");
 //stmt.execute(sql6);
 //System.out.println("ex7");
 //stmt.execute(sql7);
 //System.out.println("ex8");
 //stmt.execute(sql8);
 //System.out.println("ex9");
 //stmt.execute(sql9);
 //System.out.println("ex10");
 //stmt.execute(sql10);
 //System.out.println("ex11");
 //stmt.execute(sql11);
 //System.out.println("ex12");
 //stmt.execute(sql12);
 //System.out.println("ex13");
 //stmt.execute(sql13);
 //System.out.println("ex14");
 //stmt.execute(sql14);
 //System.out.println("ex15");
 //System.out.println("5");
 ResultSet rs = stmt.executeQuery("select Id,First_Name,Last_Name,Date_Of_Birth,Phone,Email,Qualification,Skill_Set,Company,Designation,Experience,
Salary,Location,Designation_Applied_For,Expected_Salary,Salary_Offered,Result,Interview_Date,Comments from Candidates where Id="+s16+"");
 System.out.println("6");
 while(rs.next())
 {
 out.println("<html><body bgcolor='pink'>");
 out.println("<pre>");
 out.println("The updated record set is : ");
 out.println(" ");
 out.println("Id : " + rs.getInt(1));
 out.println(" ");
 out.println("First Name : " + rs.getString(2));
 out.println(" ");
 out.println("Last Name : " + rs.getString(3));
 out.println(" ");
 out.println("Date of Birth : " + rs.getDate(4));
 out.println(" ");
 out.println("Phone : " + rs.getString(5));
 out.println(" ");
 out.println("Email : " + rs.getString(6));
 out.println(" ");
 out.println("Qualification : " + rs.getString(7));
 out.println(" ");
 out.println("Skill Set : " + rs.getString(8));
 out.println(" ");
 out.println("Company Name : " + rs.getString(9));
 out.println(" ");
 out.println("Designation : " + rs.getString(10));
 out.println(" ");
 out.println("Experience : " + rs.getFloat(11));
 out.println(" ");
 out.println("Salary : " + rs.getString(12));
 out.println(" ");
 out.println("Location : " + rs.getString(13));
 out.println(" ");
 out.println("Designation Applied For : " + rs.getString(14));
 out.println(" ");
 out.println("Expected Salary : " + rs.getString(15));
 out.println(" ");
 out.println("Salary Offered : " + rs.getString(16));
 out.println(" ");
 out.println("Result : " + rs.getString(17));
 out.println(" ");
 out.println("Interview Date : " + rs.getDate(18));
 out.println(" ");
 out.println("Comments : " + rs.getString(19));
 out.println(" ");
 out.println("<a href=http://localhost:8090/examples/servlet/OrclDb.Download?First_Name="+rs.getString(2)+"&Last_Name="+rs.getString(3)
+" target='blank'>Download Resume</a>");
 out.println(" ");
 out.println("</pre>");
 out.println("</body></html>");
 
 }
 
 
 }catch(Exception e)
 {
 out.println(e);
 }
 }
}

Using the above code i am able to update the data only if i update the Interview_Date column.Otherwise i am getting an error of type

java.sql.SQLException: ORA-01861: literal does not match format string

i am unable to figure out the problem.could somebody help me out

[edited to add code tags and line breaks]
[ October 06, 2005: Message edited by: Jeanne Boyarsky ]

If you want to update a DATE datatype (I'm guessing thats what the Interview_Date field's data type is, correct me if I'm wrong) and you are doing it with a Statement, you need to make sure that the format of the String you use to represent the date matches the format defined in the database. Now you could do this, or you could use a TO_DATE PL/SQL function, but far better is to use a PreparedStatement and bind the date. Then the format does not matter.

I would suggest, for such a big update, you should use PreparedStatement.