Transact sql (2012) Using #xml.modify to insert 'elements using a variable - sql-server

Question

I need to add an element using a variable
This works --
declare #XML xml = '
<DWDocument>
<FileInfos>
<ImageInfos>
<ImageInfo id="0,0,0" nPages="0">
<FileInfo fileName="9b7b36ac-c705-49ba-bf91-a952bdb44576.eml" dwFileName="f0.eml" type="normal" length="0" />
</ImageInfo>
<ImageInfo id="1,0,0" nPages="0">
<FileInfo fileName="Response to Deficiency Letter.docx" dwFileName="f1.docx" type="normal" length="0" />
</ImageInfo>
</ImageInfos>
</FileInfos>
</DWDocument>
'
SET #xml.modify ('insert <ImageInfo id="2,0,0" nPages="0"></ImageInfo>
as last into (DWDocument/FileInfos/ImageInfos)[1]')
Gives me:
<ImageInfo id="2,0,0" nPages="0" /><ImageInfo>
BUT...
I need the '2' to be a variable
I tried:
declare #XML xml = '
<DWDocument>
<FileInfos>
<ImageInfos>
<ImageInfo id="0,0,0" nPages="0">
<FileInfo fileName="9b7b36ac-c705-49ba-bf91-a952bdb44576.eml" dwFileName="f0.eml" type="normal" length="0" />
</ImageInfo>
<ImageInfo id="1,0,0" nPages="0">
<FileInfo fileName="Response to Deficiency Letter.docx" dwFileName="f1.docx" type="normal" length="0" />
</ImageInfo>
</ImageInfos>
</FileInfos>
</DWDocument>
'
declare #ImageInfo_ID nvarchar(50) = '"2,0,0"'
declare #ImageInfo_nPages nvarchar(50) = '"0"'
SET #xml.modify ('insert <ImageInfo id={sql:variable("#ImageInfo_ID")}></ImageInfo>
as last into (DWDocument/FileInfos/ImageInfos)[1]')
gives me the error:
Msg 2225, Level 16, State 1, Line 46
XQuery [modify()]: A string literal was expected
SET #xml.modify ('insert <ImageInfo id{sql:variable("#ImageInfo_ID")}></ImageInfo>
as last into (DWDocument/FileInfos/ImageInfos)[1]')
gives me the error
Msg 2205, Level 16, State 1, Line 48
XQuery [modify()]: "=" was expected.
SET #xml.modify ('insert <ImageInfo>{sql:variable("#ImageInfo_ID")}</ImageInfo>
as last into (DWDocument/FileInfos/ImageInfos)[1]')
has no error but the data is wrong, gives me
<ImageInfo>"2,0,0" nPages="0"</ImageInfo>
the 'id=' is missing
How do I specify the attribute name? id=#ImageInfo_ID?
What I REALLY NEED is
<ImageInfo id=#ImageInfo_ID nPages=#ImageInfo_nPages></ImageInfo>
to get to
<ImageInfo id="2,0,0" nPages="0"></ImageInfo>
What am I missing?

Answer 1

To specify the attribute name and values using variables in the XQuery expression of the modify method, you can use the sql:variable function to concatenate the attribute name and value as a string. Here's an example that should work for you:
DECLARE #ImageInfo_ID NVARCHAR(50) = '2,0,0'
DECLARE #ImageInfo_nPages NVARCHAR(50) = '0'
SET #xml.modify('
insert <ImageInfo id={sql:variable("#ImageInfo_ID")} nPages={sql:variable("#ImageInfo_nPages")}></ImageInfo>
as last into (DWDocument/FileInfos/ImageInfos)[1]'
)

Answer 2

Please try the following solution.
It is using XQuery FLWOR expression to compose needed XML.
SQL
DECLARE #xml XML =
N'<DWDocument>
<FileInfos>
<ImageInfos>
<ImageInfo id="0,0,0" nPages="0">
<FileInfo fileName="9b7b36ac-c705-49ba-bf91-a952bdb44576.eml" dwFileName="f0.eml" type="normal" length="0"/>
</ImageInfo>
<ImageInfo id="1,0,0" nPages="0">
<FileInfo fileName="Response to Deficiency Letter.docx" dwFileName="f1.docx" type="normal" length="0"/>
</ImageInfo>
</ImageInfos>
</FileInfos>
</DWDocument>';
DECLARE #ImageInfo_ID NVARCHAR(50) = '2,0,0';
DECLARE #ImageInfo_nPages NVARCHAR(50) = '0';
SET #xml = #xml.query('<DWDocument><FileInfos><ImageInfos>
{
for $x in //DWDocument/FileInfos/ImageInfos
return if ($x[position() lt last()]) then $x
else $x, <ImageInfo id="{sql:variable("#ImageInfo_ID")}" nPages="{sql:variable("#ImageInfo_nPages")}"></ImageInfo>
}
</ImageInfos></FileInfos></DWDocument>');
-- test
SELECT #xml;
Output
<DWDocument>
<FileInfos>
<ImageInfos>
<ImageInfos>
<ImageInfo id="0,0,0" nPages="0">
<FileInfo fileName="9b7b36ac-c705-49ba-bf91-a952bdb44576.eml" dwFileName="f0.eml" type="normal" length="0" />
</ImageInfo>
<ImageInfo id="1,0,0" nPages="0">
<FileInfo fileName="Response to Deficiency Letter.docx" dwFileName="f1.docx" type="normal" length="0" />
</ImageInfo>
</ImageInfos>
<ImageInfo id="2,0,0" nPages="0" />
</ImageInfos>
</FileInfos>
</DWDocument>