The argument 1 of the XML data type method "modify" must be a string literal - mysql

Question

Hi i am getting the string literal error when i am trying to add an attribute to the child node. How can i modify my code in order to add an attribute successfully.
declare #count int=(select mxGraphXML.value('count(/mxGraphModel/root/Cell/#Value )','nvarchar') from TABLE_LIST
where Table_ListID=1234 )
declare #index int=1;
while #index<=#count
begin
declare #Value varchar(100)= #graphxml.value('(/mxGraphModel/root/Cell/#Value )[1]','nvarchar');
SET #graphxml.modify('insert attribute copyValueID {sql:variable("#Value ")}
as first into (/mxGraphModel/root/Cell)['+convert(varchar,#index)+']');
end
set #index=#index+1;
end

Answer 1

You're using the addition operator where you should be using the CONCAT function. So
'insert attribute copyValueID {sql:variable("#Value ")}
as first into (/mxGraphModel/root/Cell)['+convert(varchar,#index)+']'
is being coerced into a number. Try:
CONCAT('insert attribute copyValueID {sql:variable("#Value ")}
as first into (/mxGraphModel/root/Cell)[',convert(varchar,#index),']')
instead.

Answer 2

Adam, you can do it in Microsoft T-SQL like this:
declare #sql nvarchar(max)
set #sql = 'set #myxml.modify(''
insert (
attribute scalableFieldId {sql:variable("#sf_id")},
attribute myTypeId {sql:variable("#my_type_id")}
) into (/VB/Condition/Field[#fieldId=sql:variable("#field_id")
and #fieldCode=sql:variable("#field_code")])['+
cast(#instance as varchar(3))+']'')'
exec sp_executesql
#sql
,N'#myxml xml output, #field_code varchar(20),
#field_id varchar(20), #sf_id int, #my_type_id tinyint'
,#myxml = #myxml output
,#field_code = #field_code
,#field_id = #field_id
,#sf_id = #sf_id
,#my_type_id = #my_type_id
See what I've done here? It's just a clever usage of Dynamic SQL to overcome Microsoft's moronic limitation of "string literal error".
IMPORTANT NOTE: yes, you can MOSTLY do this by using sql:variable() in SOME places BUT good luck trying to use it in the node number qualifier inside the square brackets! You can't do this without Dynamic SQL by design!
The trick is not mine actually, I got the idea from https://www.opinionatedgeek.com/Snaplets/Blog/Form/Item/000299/Read after banging my head against the wall for a while.
Feel free to ask questions if my sample does not work or something is not clear.