Stonefield Query normally expects to connect directly to SQL Server using ODBC or ADO/OLE DB. However, it's also possible to access SQL Server over HTTP if you have SQLXML installed. See the SQL Server Books Online or the MSDN Web site (http://msdn.microsoft.com) for information on SQLXML.
To use SQLXML in Stonefield Query, define a DataSource object for the database as a SQLXML data source. To do so, select the database in the TreeView and click the Create 'get data sources' script link in the properties pane. The GetDataSources script topic has an example of a SQL XML data source.