XQuery [value（）]：期望字符串文字

Question

I want to execute this code:

if exists(select * from FileUploadFileTable..sysobjects where  xtype='u' and name='##Tmp830963'  )
        drop table  ##Tmp830963
        CREATE table  ##Tmp830963 (RowId int,Files varchar(MAX) ,Files_Name NVARCHAR(MAX), Files_Size bigint,Job_Id  bigint, Files_Type VARCHAR(MAX) , User_id bigint  ,User_Name  NVARCHAR(MAX)) Insert into ##Tmp830963(RowId,Files,Files_Name,Files_Size  , Files_Type)  select A.row_num,A.Items,O.Items,B.Items,C.Items
         from(
        SELECT Items,row_number() over (order by (select 0)) as row_num
        FROM  dbo.Func_Split('/9j/AqAAAAB4CgAwAEAAABAAAAAAA', '^') ) A
        join
        (SELECT Items,row_number() over (order by (select 0)) as row_num
        FROM  dbo.Func_Split('tt^', '^') ) O  on  O.row_num=A.row_num 
         join
        (SELECT Items,row_number() over (order by (select 0)) as row_num
        FROM  dbo.Func_Split('12^', '^'))B       on  A.row_num=B.row_num 
         join
         (SELECT Items,row_number() over (order by (select 0)) as row_num
         FROM  dbo.Func_Split('png^', '^'))C
         on   C.row_num=A.row_num 
        update  ##Tmp830963 set User_Name=100update  ##Tmp830963 set Job_Id='20' update  ##Tmp830963 set User_id='1' select * from  ##Tmp830963  DECLARE @OutputTbl TABLE (ID uniqueidentifier)    INSERT INTO [Uploads]  ([file_stream],[name])  OUTPUT INSERTED.stream_id INTO @OutputTbl(ID)  select cast(N'' as xml).value('xs:base64Binary(sql:variable(Files))', 'varbinary(max)') ,Files_Name   from ##Tmp830963 while (select count(*)  from @OutputTbl) > 0 begin INSERT INTO [dbo].[FileDescriptions]  ([User_ID] ,[FileName],Stream_id,[Size],Job_Id)   select   [User_id] ,cast((select MAX(ID) from @OutputTbl   )  as nvarchar(max) ),(select MAX(ID) from @OutputTbl) , Files_Size  ,  Job_Id   from ##Tmp830963  where RowId=(select top 1(RowId) from ##Tmp830963)  delete @OutputTbl  where ID =(select MAX(ID) from @OutputTbl )  end 

But I get this error:

XQuery [value()]: A string literal was expected

On this line:

 cast(N'''' as xml).value(''xs:base64Binary(sql:variable(Files))'' 

Answer 1

On the first sight this looks a bit weird. I'm pretty sure, that this can be solved differently.

You are trying to transfer base64 to varbinary , correct?
Well, the XML-approach is the recommended way to achieve this. However, your problem seems to be situated here:

cast(N'''' as xml).value(''xs:base64Binary(sql:variable(Files))''

This is your attempt to create the needed statement dynamically, hence the doubled single quotes. This will translate to

cast(N'' as xml).value('xs:base64Binary(sql:variable(Files))'

The problem here is: sql:variable() expects the name of a declared variable as a string literal. Furthermore, value() expects two arguments: The Xpath and the data type. You'd need something like this

cast(N'' as xml).value('sql:variable("@Files")','varbinary(max)')

Might be you need sql:column("SomeColumn") , which allows to use the value of a column.

One example to demonstrate this

--We use FOR XML to get the binary 0x1234 as base64
SELECT 0x1234 FOR XML PATH(''); --returns "EjQ="

--Now I place the corresponding base64 string in a string variable 
DECLARE @base64 VARCHAR(100)='EjQ=';

--And this is, how XML is returning the binary 0x1234 from the base64-string
SELECT CAST('' AS XML).value('sql:variable("@base64")','varbinary(max)');

And this would return the same and looks a bit easier:

SELECT CAST(@base64 AS XML).value('.','varbinary(max)');

Check this for a tabular approach

The table @base64 is a declared table variable, just use your original table instead:

--Declare a table variable with one string column and insert the base64 of 0x1234
DECLARE @base64 TABLE(Files VARCHAR(100));
INSERT INTO @base64 VALUES('EjQ=');

--use the same trick as above to get the varbinary back
SELECT CAST(Files AS XML).value('.','varbinary(max)')
FROM @base64;