The argument 1 of the XML data type method “value” must be a string literal

Question

If i pass @count variable i am getting this error

Below is my query

DECLARE @Error_Description NVARCHAR(Max)
DECLARE @Count VARCHAR(20)
DECLARE @x NVARCHAR(Max)

SELECT @Error_Description = 'The external columns for Excel Source are out of synchronization with the data source columns. 
The column "szReferencceNumber" needs to be added to the external columns.
The column "SMSa" needs to be added to the external columns.
The column "as" needs to be added to the external columns.'

SELECT @Count = (LEN(@Error_Description) - LEN(REPLACE(@Error_Description, '"', ''))) / LEN('"')

SELECT @Count

SELECT COALESCE(LTRIM(CAST(('<X>' + REPLACE(@Error_Description, '"', '</X><X>') + '</X>') AS XML).value('(/X)[' + @Count + ']', 'varchar(128)')), '')

Answer 1

The first parameter to value must be a string literal. To select the nodes with a dynamic index you can do the following

SELECT 
n.value('.', 'varchar(128)') as Result
from (SELECT CAST(('<X>' + REPLACE(@Error_Description, '"', '</X><X>') + '</X>') AS XML)) ca(x)
CROSS APPLY x.nodes('(/X)') n(n)
WHERE n.value('for $l in . return count(../*[. << $l]) + 1', 'int') %2 = 0

This returns the value for every second node. So achieves your desired results of getting the values enclosed in quotes.

Result
---------------------
szReferencceNumber
SMSa
as

Answer 2

if you're using 2012+, and you can use nvarchar(4000) (not MAX) , you could get a copy of DelimitedSplitN4K_LEAD and grab rows where the value of ItemNumber is even:

DECLARE @Error_Description nvarchar(4000);

SELECT @Error_Description = N'The external columns for Excel Source are out of synchronization with the data source columns. 
The column "szReferencceNumber" needs to be added to the external columns.
The column "SMSa" needs to be added to the external columns.
The column "as" needs to be added to the external columns.';

SELECT DS.Item
FROM dbo.DelimitedSplitN4K_LEAD(@Error_Description,'"') DS
WHERE DS.ItemNumber % 2 = 0;

If you're on SQL server 2016+, then you could use some JSON manipulation (which supports MAX values):

SELECT OJ.value
FROM (VALUES(@Error_Description))V(Error_Description)
     CROSS APPLY (VALUES('["' + REPLACE(REPLACE(REPLACE(V.Error_Description,'"','","'),NCHAR(13),''),NCHAR(10),'')+ '"]'))R(JSON)
     CROSS APPLY OPENJSON(R.JSON) OJ
WHERE OJ.[Key] % 2 = 1;

Answer 3

You can use your @Count within the XQuery predicate, but not via concatenation. There is sql:variable() :

TheXml.value('(/X)[sql:variable("@Count") cast as xs:int?][1]', 'varchar(128)')

It would help to declare the variable @Count as INT in order to avoid the XQuery cast.

Hint: You need the final [1] to enforce the singleton .value() demands for.

Answer 4

this is all based on the @Shnugo answer above , thanks a lot Shnugo

I have a long script saved in to a temp table

select * from #Radhe

I want to print the whole script.

DECLARE @SQL NVARCHAR(MAX)
DECLARE @XML3 XML
--load the script to XML
SELECT @XML3 = (SELECT #Radhe.Item AS x FROM #Radhe FOR XML PATH(''))


--print line by line
declare @i int = 1
select @sql = 'radhe'

while @sql is not null
   begin
      SELECT  @sql = @xml3.value('(/x/text())[sql:variable("@i") 
                     cast as xs:int?][1]', 'varchar(max)')
      print @sql
      select @i = @i + 1
      if @i > 10000 --limit it to 10000 lines 
         set @sql = null
  end

and it works. It took me a long time to get this done. Hope I can help a fellow DBA or developer.