How do I use setString() method with multiple bind variables

Question

I have two setString() statements and a select union statement. My class compiles but only displays the data for the first table ignoring the second setString() statement. But When I replace the "where id=?" with "where id=12 or someid", it works and displays all data found in both tables.
Am I not properly using the setString() method?
public class LdData{
private String id;
public LdData(){
public void setId(String id)
    this.id = id;
  public String getId()
    return id;
public Collection getLdData() throws Exception{
                List rows = new ArrayList();
//connection statement
String sql_query="SELECT a,b FROM table1 WHERE id = ? " + " UNION " + "SELECT a,b FROM table2 WHERE id= ?";
try {
                        conn = ds.getConnection();
pstmt = conn.prepareStatement( sql_query );
pstmt.setString(1, this.id);
pstmt.setString(2, this.id);
rst = pstmt.executeQuery();
while (rst.next()) {
//dataEntry.java - contains my getter and setter
dataEntry info = new dataEntry(rst.getString("a"), rst.getString("b"), this.id);
rows.add(info);
//catch all SQLexceptions, NamingExceptions
//close all connection
return rows;
//dataEntry.java - dataEntry class
private String a;
private String b;
private String id;
public dataEntry(String a, String b, String id){
seta(a);
setb(b);
setbdate(bcode);
this.a = a;
this.b = b;
this.id = id;
public String getA(){
return a;
public String getB(){
return b;
public String getId(){
return id;
public void setA(String a){
this.a = a;
public void setB(String b){
this.b = b;
public void setId(String id){
this.id = id;
//index.jsp - displays data
<jsp:useBean id="test" class="lddata" scope="request">
<jsp:setProperty name="test" property="id" param="id"/>
</jsp:useBean>
<display:table name="${test.lddata}"/>

Answer 1

This just doesnt make sense to me at all. :( Could it be a naming issue? I mean both tables have the same field names but different data information
so the union will never sort and choose. And the weirdest thing is that
//this works -
->String sql_query="SELECT a,b FROM table1 WHERE id = TU234 " + " UNION ALL" + "SELECT a,b FROM table2 WHERE id= TU234";
//I also tried this, but the second statement doesnt work
->pstmt.setString(1, "TU234"); //this works.
->pstmt.setString(2, "TU234"); //this doesnt
//It also tried this, it worked for both set statements, but I need it in an list or so.
while (rst.next()) {
String a = rst.getString(a);
String b = rst.getString(b);
String id = rst.getString(id);
System.out.println(a+""+b+""+id);
}Is there anyother way I can collect the data into a jsp page without using javabean?