Esempio:
codice:
tabella_province
id_provincia nome_provincia sigla_provincia
1 Roma RM
2 Palermo PA
3 Catania CT
codice:
tabella_comuni
id_comune nome_comune id_provincia
1 Montecompatri 1
2 Caltagirone 3
3 Giarre 3
4 Tivoli 1
5 Bagheria 2
6 Ripi 2
La relazione tra comune e provincia èdata dal valore id_provincia presente in entrambe le tabelle.
codice:
<%@LANGUAGE="VBSCRIPT" CODEPAGE="1252"%>
<%
thisPage = request.serverVariables("PATH_INFO")
id_provincia = request.queryString("id_provincia")
if isNumeric(id_provincia) then
id_provincia = clng(id_provincia)
else
id_provincia = 0
end if
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script language="javascript" type="text/javascript">
<!--
function getProv(id){
document.location.href='<%=thisPage%>?id_provincia='+id;
}
//-->
</script>
<title>Documento senza titolo</title>
</head>
<body>
<form>
<%
set conn = server.createObject("ADODB.Connection")
conn.open "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" & server.mapPath("\database\test.mdb")
sqlProv = "SELECT id_provincia, nome_provincia FROM tabella_provincie"
set rs = conn.execute(sqlProv)
if not rs.eof then
%>
<select name="province" onChange="getProv(this.value);">
<option value="0">SELEZIONA</option>
<%
do until rs.eof
%>
<option value="<%=rs("id_provincia")%>"<% if id_provincia = rs("id_provincia") then %> selected<% end if %>><%=rs("nome_provincia")%></option>
<%
rs.moveNext
loop
%>
</select>
<%
end if
rs.close
set rs = nothing
if id_provincia > 0 then
sqlCom = "SELECT id_comune, nome_comune FROM tabella_comuni WHERE id_provincia = " & id_provincia
set rs = conn.execute(sqlCom)
if not rs.eof then
%>
<select name="comuni">
<option value="0">SELEZIONA</option>
<%
do until rs.eof
%>
<option value="<%=rs("id_comune")%>"><%=rs("nome_comune")%></option>
<%
rs.moveNext
loop
%>
</select>
<%
end if
rs.close
set rs = nothing
end if
conn.close
set conn = nothing
%>
</form>
</body>
</html>