update stringini şu şekilde yap

Degisken=Request.Form("degisken")

Set Guncelle=Server.CreateObject("ADODB.Recordset")
sql="SELECT * FROM tablom"
Guncelle.Open sql,Baglanti,1,3

Guncelle.Update
Guncelle("hucre")=Degisken
Guncelle.Update

Guncelle.Close : Set Guncelle=Nothing

Response.redirect "default.asp"