Need help on combo box problem

Question

hi ,
i have two combo box..... eg..c1,c2
i retrieved data from database to display it in combo box c1.now my problem is using the selected value from combo box c1 i have to display the respective value in c2..
eg.
if Product type=injection (in combo box c1)
then
in c2 the product name for injection available should be displayed by retrieving it from database...
this is my code
<%
//query for selecting the values from the database
stm=con.createStatement();
ResultSet rs=stm.executeQuery("select Dosageform from ProductMaster");
%>
<!-- Displaying the values in the combo box -->
<form name="form1" method="post" action="">  <select name="eid" id="eid" onchange="display(this)">
<%
while(rs.next())
%>
<OPTION VALUE=""><%=rs.getString("Dosageform")%></OPTION>
<%
%>
</select>
<select name="combo2">
               </select>i don't know how to write the function display for this....
can any one help me...
Thanks
kalai

Answer 1

hi
thanx to all who sees my forum.
now i was able to create a depenent box but now i'm facing two problems
1. when i submit the form my previous value from the combo box is not selected
2. when i first load the page the value in the 2nd combo box doesn't has the value as null...
my code
function display()
  var index=document.form1.drug.value;
  document.form1.hid.value=index;
  form1.submit();
function refresh()
   var val;
   val=document.form1.hid.value;
   drug.SelectedIndex=value;
<div class="tr1">
<td>Product Name</td>
<%
//query for selecting the values from the database
   rs=stm.executeQuery("select DrugName from ProductMaster");
%>
<!-- Displaying the values in the combo box -->
<form name="form1" method="post" action="">
<select name="drug" id="drug" onChange="display()">
<option value="">-- select -- </option>
<%
while(rs.next())
%>
<OPTION VALUE="<%=rs.getString("DrugName")%>"><%=rs.getString("DrugName")%></OPTION>
<%
%>
</select>
<input type="hidden" name="hid">
</div>
</tr>
<tr>
<div class="td1">
<td>NDC code #</td>
<%
//query for selecting the values from the database
String sql1 = "SELECT ProductCode from ProductMaster where DrugName='"+request.getParameter("hid")+"' ";
rs=stm.executeQuery(sql1);
%>
<SELECT NAME='ndc'>
<% while (rs.next())
String val1=rs.getString("ProductCode");
out.println ("<OPTION VALUE='" + val1 + "'>" + val1 + "</OPTION>");
%>
</div>i don't know wht to do...
pls help me as soon as u can...
Thanks & Regards
kalai