Insert/Delete in a servlet to dbase - URGENT!!

Question

I have an urgent question. If I use a query to select from values based on a variable from a JSP (subject code)...... and then based on the values returned by this query (i.e code, year and semester,unit) I then want to add/delete these values to a new table (called chosensubject), based on whether they chose the variable drop or add in the JSP!!
How do I do this???
I am using a servlet which picks up the data from a JSP after it is submitted to the server.
Please Help!
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.DriverManager;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class loginAssign2 extends HttpServlet
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
//get the parametes from the JSP page
String sem1c1 = request.getParameter("Sem1#1").trim();
String us = request.getParameter("username").trim();
String sem1c2 =request.getParameter("Sem1#2").trim();
String sem1c3 = request.getParameter("Sem1#3").trim();
String sem1c4 = request.getParameter("Sem1#4").trim();
String sem2c1 = request.getParameter("Sem2#1").trim();
String sem2c2 = request.getParameter("Sem2#3").trim();
String sem2c3 = request.getParameter("Sem2#3").trim();
String sem2c4 = request.getParameter("Sem2#4").trim();
String userID = request.getParameter("userID").trim();
String Drop1 = request.getParameter("drop1").trim();
String Drop2 = request.getParameter("drop2").trim();
String Drop3 = request.getParameter("drop3").trim();
String Drop4 = request.getParameter("drop4").trim();
String Drop5 = request.getParameter("drop5").trim();
String Drop6 = request.getParameter("drop6").trim();
String Drop7 = request.getParameter("drop7").trim();
String Drop8 = request.getParameter("drop8").trim();
String sqlQuery;
String sqlQuery2;
if (sem1c1 !="") {
sqlQuery = "select*from tmpoffering where code = '" + sem1c2 + "'";
// Iterate through the result and verify the password
response.setContentType("text/html");
PrintWriter out = response.getWriter();
Connection conn = null;
try {   
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection("jdbc:oracle:thin:@Midas2:1521:globaldb", "system", "manager");
catch (Exception e) {
out.println("Cannot close connect to database!"+e);
if (conn != null) {
try { // execute the query
Statement stmt = conn.createStatement();
ResultSet rst;
rst = stmt.executeQuery(sqlQuery);
// Fetch the query result, and dispaly them in a table
while (rst.next()) {
<<Need help here!!!! Think I need an if statement (i.e if 'drop' then delete otherswise if 'add' then insert!!!... but how do I put it into a servlet??)
     sqlQuery2 = "insert into subjectchoosen values ('code','year','sem','userID') ";
stmt.close();
} catch(Exception e) {
     out.println("Cannot fetch data from database!"+e);
out.println("</table>");
out.println("</body></html>");

Answer 1

If the servlet is within an application container,
you can locate a data source create a SQL connection an execue a query.
DataSource ds =  (DataSource) (new InitialContetx()).lookup("my_ds");
Connection conn = ds.getConnection();if it is only a web server
/** sample using JSQLDriver */
Connection conn = null;
Statment stmt = null;
ResultSet rs = null;
try {
  Class.forName("com.jnetdirect.jsql.JSQLDriver");
  conn = DriverManager.getConnection(
          "jdbc:JSQLConnect://localhost/database=master",
          "sa",
  stmt = conn.createStatement();
  rs = stmt.executeQuery("select * from my_table");
} finally {
  try {
    if (rst != null) {
      rs.close();
    if (stmt != null) {
      stmt.close();
    if (conn != null) {
        conn.close();
  catch (SQLException ex2) {
}