Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

that throughout the Updategram. The nullvalue attribute indicatesthe alternative text, as shown here:...Submitting Commands Through UpdategramsUpdategrams can be executed in various ways. You can send the Updategram text toSQL Server over HTTP. Alternatively, you can write the XML contents out to a file andthen point the browser (or any other HTTP-enabled software) to that URL so that thecontents are executed. Or you can use an Updategram with ADO.The following Visual Basic 6.0 code shows how to proceed. Notice that you must copythe Updategram to a stream and receive the response over another stream object.Dim cmd As New ADODB.CommandDim conn As New ADODB.ConnectionDim strIn As New ADODB.StreamDim strOut As New ADODB.Streamconn.Provider = "SQLOLEDB"conn.Open "SERVER=localhost;DATABASE=northwind;UID=sa;"conn.Properties("SQLXML Version") = "SQLXML.3.0"Set cmd.ActiveConnection = conncmd.Dialect = "{5d531cb2-e6ed-11d2-b252-00c04f681b71}"strIn.OpenstrIn.WriteText SQLxmlstrIn.Position = 0Set cmd.CommandStream = strInstrOut.Opencmd.Properties("Output Stream").Value = strOutcmd.Properties("Output Encoding").Value = "UTF-8"cmd.Execute , , adExecuteStreamNotice also that you need to set the command dialect to a particular globally uniqueidentifier (GUID)—DBGUID_MSSQLXML—and set a few properties on the commandand the connection objects.Concurrency IssuesUpdategrams are batches that work by looping on source data and executing asequence of commands. What happens if, due to the system concurrency, rows thatyou are going to modify have been changed since the time you last read them?312