Secondary data sources in Microsoft Office InfoPath are XML
files, databases, SharePoint lists, or web services that have been linked to an
InfoPath form, but for which no data is persisted in the form itself. Therefore,
any changes made to the data of a secondary data source are lost upon closing
the form, unless these changes have been saved back to the underlying data
store of the secondary data source.
and XML, better known as AJAX, to permanently update data in a secondary data
source for which the underlying source is a database table in Microsoft SQL