SQL Server：从VARCHAR(MAX)字段替换无效的XML字符

我有一个VARCHAR(MAX)字段,它以XML格式连接到外部系统.接口抛出以下错误：

mywebsite.com-2015-0202.xml:413005: parser error : xmlParseCharRef: invalid xmlChar value 29
ne and Luke's family in Santa Fe. You know you have a standing invitation,
                                                                               ^
mywebsite.com-2015-0202.xml:455971: parser error : xmlParseCharRef: invalid xmlChar value 25
The apprentice nodded,because frankly,who hadnt? That diseases like chol
                                                      ^
mywebsite.com.com-2015-0202.xml:456077: parser error : xmlParseCharRef: invalid xmlChar value 28
bon mot; a sentimental love of nature and animals; the proverbial British 
                                                                               ^
mywebsite.com-2015-0202.xml:472073: parser error : xmlParseCharRef: invalid xmlChar value 20
"Andyou want that?"
          ^
mywebsite.com-2015-0202.xml:492912: parser error : xmlParseCharRef: invalid xmlChar value 25
She couldnt live like this anymore.

我们发现以下字符列表无效：

�








	

























我正在尝试清理这些数据,并且我找到了一个SQL函数来清理这些字符here.但是,该函数将NVARCHAR(4000)作为输入参数,因此我将函数更改为使用VARCHAR(MAX).

有人可以建议将NVARCHAR(4000)更改为VARCHAR(MAX)会产生错误的结果吗？对不起,我无法在本地测试此界面,所以想要寻求意见/建议.

原始功能：

CREATE FUNCTION fnStripLowAscii (@InputString nvarchar(4000))
RETURNS nvarchar(4000)
AS
BEGIN
IF @InputString IS NOT NULL
BEGIN
  DECLARE @Counter int,@TestString nvarchar(40)

  SET @TestString = '%[' + NCHAR(0) + NCHAR(1) + NCHAR(2) + NCHAR(3) + NCHAR(4) + NCHAR(5) + NCHAR(6) + NCHAR(7) + NCHAR(8) + NCHAR(11) + NCHAR(12) + NCHAR(14) + NCHAR(15) + NCHAR(16) + NCHAR(17) + NCHAR(18) + NCHAR(19) + NCHAR(20) + NCHAR(21) + NCHAR(22) + NCHAR(23) + NCHAR(24) + NCHAR(25) + NCHAR(26) + NCHAR(27) + NCHAR(28) + NCHAR(29) + NCHAR(30) + NCHAR(31) + ']%'

  SELECT @Counter = PATINDEX (@TestString,@InputString COLLATE Latin1_General_BIN)

  WHILE @Counter <> 0
  BEGIN
    SELECT @InputString = STUFF(@InputString,@Counter,1,NCHAR(164))
    SELECT @Counter = PATINDEX (@TestString,@InputString COLLATE Latin1_General_BIN)
  END
END
RETURN(@InputString)
END

修改版本：

CREATE FUNCTION [dbo].RemoveInvalidXMLCharacters (@InputString VARCHAR(MAX))
RETURNS VARCHAR(MAX)
AS
BEGIN
    IF @InputString IS NOT NULL
    BEGIN
      DECLARE @Counter INT,@TestString NVARCHAR(40)

      SET @TestString = '%[' + NCHAR(0) + NCHAR(1) + NCHAR(2) + NCHAR(3) + NCHAR(4) + NCHAR(5) + NCHAR(6) + NCHAR(7) + NCHAR(8) + NCHAR(11) + NCHAR(12) + NCHAR(14) + NCHAR(15) + NCHAR(16) + NCHAR(17) + NCHAR(18) + NCHAR(19) + NCHAR(20) + NCHAR(21) + NCHAR(22) + NCHAR(23) + NCHAR(24) + NCHAR(25) + NCHAR(26) + NCHAR(27) + NCHAR(28) + NCHAR(29) + NCHAR(30) + NCHAR(31) + ']%'

      SELECT @Counter = PATINDEX (@TestString,@InputString COLLATE Latin1_General_BIN)

      WHILE @Counter <> 0
      BEGIN
        SELECT @InputString = STUFF(@InputString,' ')
        SELECT @Counter = PATINDEX (@TestString,@InputString COLLATE Latin1_General_BIN)
      END
    END
    RETURN(@InputString)
END

解决方法

在这里你的邪恶名单

DECLARE @evilChars VARCHAR(MAX)=
  CHAR(0x0)
+ CHAR(0x1)
+ CHAR(0x2)
+ CHAR(0x3)
+ CHAR(0x4)
+ CHAR(0x5)
+ CHAR(0x6)
+ CHAR(0x7)
+ CHAR(0x8)
+ CHAR(0x9)
+ CHAR(0xa)
+ CHAR(0xb)
+ CHAR(0xc)
+ CHAR(0xd)
+ CHAR(0xe)
+ CHAR(0xf)
+ CHAR(0x10)
+ CHAR(0x11)
+ CHAR(0x12)
+ CHAR(0x13)
+ CHAR(0x14)
+ CHAR(0x15)
+ CHAR(0x16)
+ CHAR(0x17)
+ CHAR(0x18)
+ CHAR(0x19)
+ CHAR(0x1a)
+ CHAR(0x1b)
+ CHAR(0x1c)
+ CHAR(0x1d)
+ CHAR(0x1e)
+ CHAR(0x1f)
+ CHAR(0x7f);

这很有效

DECLARE @XmlAsString NVARCHAR(MAX)=
(
    SELECT @evilChars FOR XML PATH('test')
);
SELECT @XmlAsString;

结果(一些是“打印”)

<test>&#x00;&#x01;&#x02;&#x03;&#x04;&#x05;&#x06;&#x07;&#x08;    
&#x0B;&#x0C;&#x0D;&#x0E;&#x0F;&#x10;&#x11;&#x12;&#x13;&#x14;&#x15;&#x16;&#x17;&#x18;&#x19;&#x1A;&#x1B;&#x1C;&#x1D;&#x1E;&#x1F;</test>

以下是禁止的

SELECT CAST(@XmlAsString AS XML)

但是您可以使用VARBINARY到base64的隐式转换

DECLARE @base64 NVARCHAR(MAX)=
(
    SELECT CAST(@evilChars AS VARBINARY(MAX)) FOR XML PATH('test')
);
SELECT @base64;

结果

<test>AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh9/</test>

现在你已经拥有了真正的XML,包括特殊字符！

SELECT CAST(CAST(@base64 AS XML).value('/test[1]','varbinary(max)') AS VARCHAR(MAX)) FOR XML PATH('reconverted')

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