generating dynamic/runtime query

I want to generate a code that will automatically take the poll-id..of which the user wishes to view the result of that poll. there's the code:using mysql & java & another thing i wish to use this on a jsp page:

package votepiepack;
    
   import java.sql.Connection;
   import java.sql.DriverManager;
   import java.sql.*;
   import org.jfree.chart.*;
   import org.jfree.data.jdbc.*;
   import org.jfree.data.general.*;
    
    
   public class votepie {
    
               /**
                * @param args
                */
               
               private PieDataset readData() {
                           JDBCPieDataset data = null;
                           String url = "jdbc:mysql://localhost/vote";
                           Connection con;
                           try {
                           Class.forName("com.mysql.jdbc.Driver");
                           }
                           catch (ClassNotFoundException e) {
                           System.err.print("ClassNotFoundException: ");
                           System.err.println(e.getMessage());
                           }
                           try {
                           con = DriverManager.getConnection(url, "vote", "vote001");
                           data = new JDBCPieDataset(con);
                           String sql = "SELECT option_text, counter FROM VOTE_VOTES WHERE poll-id=1;";
                           data.executeQuery(sql);
                           con.close();
                           }
                           catch (SQLException e) {
                           System.err.print("SQLException: ");
                           System.err.println(e.getMessage());
                           }
                           catch (Exception e) {
                           System.err.print("Exception: ");
                           System.err.println(e.getMessage());
                           }
                           return data;
                           }
               public static void main(String[] args) {
                           // TODO Auto-generated method stub
                           
                           votepie pd = new votepie();
                           pd.readData();
                           
                           //creating the chart
                           JFreeChart chart = ChartFactory.createPieChart(
                                                   "Sample Pie Chart",
                                                   pd.readData(),
                                                   true, // legend?
                                                   true, // tooltips?
                                                   false // URLs?
                                                   );
                                                   // create and display a frame...
                                                   ChartFrame frame = new ChartFrame("First", chart);
                                                   frame.pack();
                                                   frame.setVisible(true);
    
               }
    
   }

as you can see I can view only 1 result at a time.

String sql = "SELECT option_text, counter FROM VOTE_VOTES WHERE poll-id=1;";

but how is it possible to capture the poll-id on which the user wishes to click & show the result of that poll....is it by using "placeholders" if yes how? or any other, please suggest..thanks

ps: donno where to post so posting both on mysql & java forums.