Question

我要执行以下代码：

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

但是我得到这个错误：

XQuery [value（）]：应该是字符串文字

在这一行：

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

Answer 1

乍一看，这看起来有点不可思议。我很确定，这可以用其他方法解决。

您正在尝试将base64转移到varbinary，对吗？
好吧，XML方法是实现此目的的推荐方法。但是，您的问题似乎出在这里：

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

这是您尝试动态创建所需语句的尝试，因此将单引号加倍。这将转换为

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

这里的问题是：sql:variable()期望声明的变量的名称为字符串文字。此外，value()需要两个参数：Xpath和数据类型。您需要像这样的东西

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

可能需要sql:column("SomeColumn")，它允许使用列的值。

一个例子来证明这一点

--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)');

这将返回相同的结果，并且看起来更简单：

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

选中此表格即可

表@base64是声明的表变量，只需使用原始表即可：

--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;

XQuery [value（）]：应该是字符串文字

1 个答案:

一个例子来证明这一点

选中此表格即可