提取二进制数据时存储的空值

Question

我有一个表Employee，其中SQL列中的列为Id(bigint)和DocumentContent(varbinary(MAX))。

现在，当我尝试在使用XML的Employee表中插入记录时，Null值存储在大小小于1Kb的文件的表中。当文件大小大于1Kb时，它将被转换为二进制数据并存储在数据库中。产生

我的XML如下：

<MyDocuments> 
    <Rows> 
    <Id>62</Id> 
    <Document_Content>104116116112584747495550464954464846495856485748471041161161129910810510111011646104116109108</Document_Content> 
    </Rows> 
</MyDocuments> 

和存储过程

CREATE Procedure [dbo].[Proc_SaveDocuments] 
( 
@XMLData as XML 
) 
AS 
BEGIN 
Declare @propertyCount Varchar(100) = '',@currentCount int=1,@Id bigint,@Content varbinary(MAX) 
SELECT @propertyCount = convert(VARCHAR, @XMLData.query ('count(/MyDocuments/Rows)')) 
SET @currentCount = 1 
    WHILE (@currentCount<=@propertyCount)  
    BEGIN 
    SET @Id = @XMLData.value('data(/MyDocuments/Rows[sql:variable("@currentCount")]/Id)[1]', 'BIGINT') 
    SET @Content = @XMLData.value('data(/MyDocuments/Rows[sql:variable("@currentCount")]/Document_Content)[1]', 'VARBINARY(MAX)') 

    insert into Employee values(@Id,@Content) --inserts null in DocumentContent column when file size less than 1Kb, else converts it to binary and saves it in database. 
    SET @currentCount = @currentCount + 1 
    END 
END 

任何想法，为什么会出现这种情况，如何可以这样解决？

Answer 1

我认为XML不明白 “VARBINARY” 格式：

DECLARE @XMLData XML = '<MyDocuments> 
    <Rows> 
    <Id>62</Id> 
    <Document_Content>104116116112584747495550464954464846495856485748471041161161129910810510111011646104116109108</Document_Content> 
    </Rows> 
    <Rows> 
    <Id>63</Id> 
    <Document_Content>654654654654546847435483797123954898327987329759873256327864929347623974311011646104116109108</Document_Content> 
    </Rows> 
</MyDocuments>' 

Declare @propertyCount Varchar(100) = '',@currentCount int=1,@Id bigint,@Content varbinary(MAX) 
SELECT @propertyCount = convert(VARCHAR, @XMLData.query ('count(/MyDocuments/Rows)')) 
SET @currentCount = 1 

SELECT @propertyCount = convert(VARCHAR, @XMLData.query ('count(/MyDocuments/Rows)')) 
SET @currentCount = 1 
WHILE (@currentCount<=@propertyCount)  
BEGIN 

    SET @Id = @XMLData.value('data(/MyDocuments/Rows\[sql:variable("@currentCount")\]/Id)\[1\]', 'BIGINT') 
    SET @Content = CAST(@XMLData.value('data(/MyDocuments/Rows\[sql:variable("@currentCount")\]/Document_Content)\[1\]', 'VARCHAR(MAX)') as VARBINARY(MAX)) 

    SET @currentCount += 1 
    SELECT @Id,@Content 
END]