Using Xquery to replace a node value that is xsi:nil = "true"

I am trying to use XQuery in SQL Server 2005 to update xml saved in a column. Here is a sample of the data I need to update.

<Length>3</Length>
<Width>5</Width>
<Depth>6</Depth>
<Area xsi:nil="true" />
<Volume xsi:nil="true" />

I need to set the area and volume to values from a different table. I am creating a CTE for the update. There is other logic that I have omitted, but I have verified that the CTE contains the correct data for the update:

;with Volume (DocumentID, Volume) As
(
  Select DocumentID, Volume from tbl
)

and I am using the following XQuery SQL statement to try to update the table.

UPDATE tbl_Archive
   SET XML.modify(' declare namespace x="http://www.redacted.com";
   replace va开发者_如何转开发lue of  (/x:Document/x:Volume/text())[1]
   with sql:column("Volume.Volume")')
    From Volume where volume.documentID = tbl_Archive.DocumentID

I get 1 row affected, but when I look at the XML it hasn't changed, and I can't figure out what needs to be fixed to make it work. The node is untyped, if that makes any difference.

---

Update wont work if there's no text to replace.. the XPath /x:Document/x:Volume/text())[1] will return an empty set.

Try insert...

UPDATE tbl_Archive
   SET XML.modify(' declare namespace x="http://www.redacted.com";
   insert text {sql:column("Volume.Volume")}
   as first into  (/x:Document/x:Volume)[1]')
    From Volume where volume.documentID = tbl_Archive.DocumentID

..you'll then need to remove the nil="true" attribute..

Something like this maybe..

 update tbl_Archive set XML.modify('delete /*:Document/*:Volume[text()]/@xsi:nil')