获取二进制数据时存储的空值

Question

我有一个表 Employee，在 SQL 中包含 Id(bigint) 和 DocumentContent(varbinary(MAX)) 列。

现在，当我尝试使用 XML 在 Employee 表中插入记录时，Null 值存储在表中，用于大小小于 1Kb 的文件。当文件大小大于1Kb时，它被转换为二进制数据并存储在数据库中。

我生成的XML如下：

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

存储过程是

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

任何想法为什么会发生这种情况以及如何解决？

Answer 1

我假设 XML 不理解“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]