Question about Querying by "for xml auto" and retriving xml by Str

The following function works fine for 2 years but recently it crashes several
times
and the error message is "Object reference not set to an instance of an
object."
The SQL query works fine in SQL server 2000. OS is Windows server 2003, and
this
function is used in ASP.Net project.
Can somebody figure it out? Your help is highly appreciated!
Public Function get_cart_number() As String
Dim cmd As New Command()
Dim conn As New Connection()
Dim strmIn As New Stream()
Dim strmOut As New Stream()
Dim SQLxml As String
Dim xml As New XmlDocument()
Dim strTemp As String
' Open a connection to the SQL Server.
conn.Open("Provider=SQLOLEDB; server=someServer; uid=uid; pwd=pwd;
database=someDB;")
cmd.ActiveConnection = conn
'Build the command string in the form of an XML template
SQLxml = "<root
xmlns:sql=""urn:schemas-microsoft-com:xml-sql""><sql:query>"
SQLxml = SQLxml & "select distinct cart_number from Cart for xml auto"
SQLxml = SQLxml & "</sql:query></root>"
' Set the command dialect to XML.
cmd.Dialect = "{5d531cb2-e6ed-11d2-b252-00c04f681b71}"
' Open the command stream and write our template to it.
strmIn.Open()
strmIn.WriteText(SQLxml)
strmIn.Position = 0
cmd.CommandStream = strmIn
' Execute the command, open the return stream, and read the result.
strmOut.Open()
strmOut.LineSeparator = adCRLF
cmd.Properties("Output Stream").Value = strmOut
cmd.Execute(, , adExecuteStream)
strmOut.Position = 0
xml.LoadXml(strmOut.ReadText)
Dim cart As XmlNode
For Each cart In xml.SelectSingleNode("root").ChildNodes
strTemp = strTemp & "<cart>" & cart.Attributes(0).Value.ToString
& "</cart>"
Next
strmIn.Close()
strmOut.Close()
Return (strTemp)
End Function
I don't know what line that this is failing on, but if I had to guess, I
think it would be in this area:

> For Each cart In xml.SelectSingleNode("root").ChildNodes
> strTemp = strTemp & "<cart>" &
cart.Attributes(0).Value.ToString & "</cart>"
> Next
You probably have some NULL values and therefore aren't bringing back the
attribute value that you are trying to retrive here:
"cart.Attributes(0).Value". I would check the results of the query first.
Jay Nathan
http://www.jaynathan.com/blog
"Ruopian" <Ruopian@.discussions.microsoft.com> wrote in message
news:35A167A6-1ECB-485D-A916-2B1A7690DA4C@.microsoft.com...
> The following function works fine for 2 years but recently it crashes
several
> times
> and the error message is "Object reference not set to an instance of an
> object."
> The SQL query works fine in SQL server 2000. OS is Windows server 2003,
and
> this
> function is used in ASP.Net project.
> Can somebody figure it out? Your help is highly appreciated!
> Public Function get_cart_number() As String
> Dim cmd As New Command()
> Dim conn As New Connection()
> Dim strmIn As New Stream()
> Dim strmOut As New Stream()
> Dim SQLxml As String
> Dim xml As New XmlDocument()
> Dim strTemp As String
> ' Open a connection to the SQL Server.
> conn.Open("Provider=SQLOLEDB; server=someServer; uid=uid; pwd=pwd;
> database=someDB;")
> cmd.ActiveConnection = conn
> 'Build the command string in the form of an XML template
> SQLxml = "<root
> xmlns:sql=""urn:schemas-microsoft-com:xml-sql""><sql:query>"
> SQLxml = SQLxml & "select distinct cart_number from Cart for xml
auto"
> SQLxml = SQLxml & "</sql:query></root>"
> ' Set the command dialect to XML.
> cmd.Dialect = "{5d531cb2-e6ed-11d2-b252-00c04f681b71}"
> ' Open the command stream and write our template to it.
> strmIn.Open()
> strmIn.WriteText(SQLxml)
> strmIn.Position = 0
> cmd.CommandStream = strmIn
> ' Execute the command, open the return stream, and read the
result.
> strmOut.Open()
> strmOut.LineSeparator = adCRLF
> cmd.Properties("Output Stream").Value = strmOut
> cmd.Execute(, , adExecuteStream)
> strmOut.Position = 0
> xml.LoadXml(strmOut.ReadText)
> Dim cart As XmlNode
> For Each cart In xml.SelectSingleNode("root").ChildNodes
> strTemp = strTemp & "<cart>" &
cart.Attributes(0).Value.ToString
> & "</cart>"
> Next
> strmIn.Close()
> strmOut.Close()
> Return (strTemp)
> End Function
>
>