InfoPath Dev

i mangage to fix it with this using the timestamp to identify the field thanks anyway xdXDocument:GetDOM("Live$Vendor")/dfs:myFields/dfs:dataFields/d:Live_Vendor/@Phone_No_[../@timestamp = xdXDocument:get-DOM()/my:PurchaseOrder/my:FirstDetails/my:SupplierSelect]

Ok so i'm new to this but i will try to describe as much as possible.  My aim is to have a dropdown box with supplier names in, this is populated via an SQL query, also i want to display the supplier phone number from the same sql query in another textbox based on the supplier selection.  In simple terms there is a dropdown ...