SQL：使用 modify 函数迭代 xml 节点或如何递归地插入或修改节点

Question

我有一个xml，如下面的代码所示

我想遍历每个节点并在每个 TextReadingName 节点之后插入一个节点

DECLARE @XML XML =
N'<Steplist>
  <Step>
    <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>     
  </Step>
  <Step>
    <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
  </Step>
</Steplist>';



--SELECT x.XmlCol.value('(StepId)[1]', 'nvarchar(max)') as StepId
--FROM   @xml.nodes('/Steplist/Step') x(XmlCol)  

这就是我希望我的新 xml 的外观

N'<Steplist>
      <Step>
        <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
        <Rank>1</Rank>
        <IsComplete>false</IsComplete>
        <TextReadingName>bug-8588_Updated3</TextReadingName>    
      <TextReadingId>1</TextReadingId>   
      </Step>
      <Step>
        <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
        <Rank>2</Rank>
        <TextReadingName>reading1</TextReadingName>
      <TextReadingId>2</TextReadingId> 
      </Step>
    </Steplist>';

我可以选择如下所示的节点，但无法遍历每个节点并修改数据

--SELECT x.XmlCol.value('(StepId)[1]', 'nvarchar(max)') as StepId
--FROM   @xml.nodes('/Steplist/Step') x(XmlCol) 

我正在寻找与上面相同的功能，但用于插入节点

这就是我希望我的新 xml 在 TextReading 名称之后使用名为 TextReadingId 的新节点的方式

N'<Steplist>
      <Step>
        <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
        <Rank>1</Rank>
        <IsComplete>false</IsComplete>
        <TextReadingName>bug-8588_Updated3</TextReadingName>    
      <TextReadingId>1</TextReadingId>   
      </Step>
      <Step>
        <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
        <Rank>2</Rank>
        <TextReadingName>reading1</TextReadingName>
      <TextReadingId>2</TextReadingId> 
      </Step>
    </Steplist>';

Answer 1

您可以将modify 与insert 一起使用，但主要缺点似乎是SQL server 只允许insert 进入单个节点，我无法将它与FLOWR 表达式组合，所以我不得不使用一个 SQL WHILE 循环来执行各种modify 调用：

DECLARE @XML XML =
N'<Steplist>
  <Step>
    <StepId>e36a3450-1c8f-44da-b4d0-58e5bfe2a987</StepId>
    <Rank>1</Rank>
    <IsComplete>false</IsComplete>
    <TextReadingName>bug-8588_Updated3</TextReadingName>     
  </Step>
  <Step>
    <StepId>4078c1b1-71ea-4578-ba61-d2f6a5126ba1</StepId>
    <Rank>2</Rank>
    <TextReadingName>reading1</TextReadingName>
  </Step>
</Steplist>';

BEGIN

DECLARE @i int;

SELECT @i = @XML.value('count(Steplist/Step)', 'int');

WHILE @i > 0
  BEGIN

    SET @XML.modify('insert <TextReadingId>{sql:variable("@i")}</TextReadingId> as last into (/Steplist/Step[sql:variable("@i")])[1]');

    SET @i = @i - 1;
  END
END
SELECT @XML;