You can test the demo for dynamically dependent dropdown boxes here:
http://www.jamesfarrow.com/codeexamples/Double_Listbox_Populated_From_DB/
Download Source & Access Database Used:
http://www.jamesfarrow.com/codeexamples/Double_Listbox_Populated_From_DB/this.zip.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Dependent Dropdownlists</title>
<%
Dim myConnection 'Object
Dim myRS 'Object
Dim myConnectString 'String
Dim mySQL 'String
Dim StartAuthor 'String
Dim Cnt 'Integer
Dim ListBox1 'String
'Database Connect String
myConnectString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source="&Server.MapPath("author.mdb")
'Make Javascript Function to handle ListBox 2
%>
<script language="javascript">
function listboxchange(p_index)
{
<%
'SQL Statement which groupes all authors together, to handle more than 1 book per author
mySQL = "SELECT * FROM Library Order By Author asc"
Set myConnection = CreateObject("ADODB.Connection")
myConnection.open myConnectString
'Get Recordset using our SQL
Set myRS = myConnection.Execute(mySQL)
%>
switch (p_index)
{
<%
'Loop Through all authors and books
Do Until myRS.eof
StartAuthor = myRS("Author")
Cnt = 0
%>
case "<%=StartAuthor%>" :
<%
'Loop until we disover a new author. Whilst author the same, add all of his/her books into grouped selection
do until myrs.eof or StartAuthor <> myRS("Author")
%>
document.myform.listbox2.options[<%=cnt%>]=new Option("<%=myRs("Book")%>","<%=myRs("Book")%>");
<%
Cnt = Cnt + 1
myrs.movenext
if myrs.eof then exit do
Loop
%>
break;
<%
Loop
myRS.close
Set myRS = nothing
%>
}
return true;
}
</script>
<%
'Make ListBox1
'SQL Statement which selects each database entry for an author just once
'as we don't want the same name twice in our list box
mySQL = "SELECT DISTINCT Author FROM Library Order By Author asc"
Set myConnection = CreateObject("ADODB.Connection")
myConnection.open myConnectString
Set myRS = myConnection.Execute(mySQL)
'Make Drop down box Author list
do until myrs.eof
ListBox1 = ListBox1 & "<option value=""" & myRs("Author") & """>" & myRs("Author") & "</option>"
myRs.movenext
loop
myRS.close
Set myRS = nothing
myConnection.close
Set myConnection = nothing
%>
</head>
<body>
<form name="myform" action="" method="get">
<select name="listbox1" id="listbox1" onchange="javascript: listboxchange(this.options[this.selectedIndex].value);">
<option value="">Please Select</option>
<%=ListBox1%>
</select>
<select name="listbox2">
<option value="">Please Select</option>
</select>
</form>
</body>
</html>
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