从执行计划中切割XML

Question

我会在前言中说我讨厌XML，可怕的东西，但有时需要。

我目前的问题是，我试图从一个执行计划（由用户提供，所以可能是任何大小）采取XML，并将其粉碎成表格进一步操纵。目前我有两种选择;

1. 我可以计算可用于执行计划的最大节点数量（我怀疑这会很多）并创建可用于任何XML输入的整个脚本。这将是一次性的事情，所以不是一个问题。
2. 另一种方法是动态调整节点的数量并根据需求创建输出。

有没有人在过去做过类似的练习？我发现的所有示例查询都已知输出字段。

Answer 1

一个很直的方式可能是这个（当@x是你的XML的执行计划）：

DECLARE @x XML= 
N'<root> 
    <ElementE1 AttributA1="A1-text belongs to E1[1]" OneMore="xyz">E1-Text 2</ElementE1> 
    <ElementE1 AttributA1="A1-text belongs to E1[2]">E1-Text 2</ElementE1> 
    <ElementParent> 
     <subElement test="sub"/> 
     Free text 
    </ElementParent> 
    </root>'; 

DECLARE @idoc INT; 
EXEC sp_xml_preparedocument @idoc OUTPUT, @x; 
SELECT * FROM OPENXML (@idoc, '*'); 
EXEC sp_xml_removedocument @idoc; 

结果（不是所有列）

+----+----------+----------+--------------+------+--------------------------+ 
| id | parentid | nodetype | localname | prev | text      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 0 | NULL  | 1  | root   | NULL | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 2 | 0  | 1  | ElementE1 | NULL | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 3 | 2  | 2  | AttributA1 | NULL | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 13 | 3  | 3  | #text  | NULL | A1-text belongs to E1[1] | 
+----+----------+----------+--------------+------+--------------------------+ 
| 4 | 2  | 2  | OneMore  | NULL | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 14 | 4  | 3  | #text  | NULL | xyz      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 5 | 2  | 3  | #text  | NULL | E1-Text 2    | 
+----+----------+----------+--------------+------+--------------------------+ 
| 6 | 0  | 1  | ElementE1 | 2 | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 7 | 6  | 2  | AttributA1 | NULL | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 15 | 7  | 3  | #text  | NULL | A1-text belongs to E1[2] | 
+----+----------+----------+--------------+------+--------------------------+ 
| 8 | 6  | 3  | #text  | NULL | E1-Text 2    | 
+----+----------+----------+--------------+------+--------------------------+ 
| 9 | 0  | 1  | ElementParent| 6 | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 10 | 9  | 1  | subElement | NULL | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 11 | 10  | 2  | test   | NULL | NULL      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 16 | 11  | 3  | #text  | NULL | sub      | 
+----+----------+----------+--------------+------+--------------------------+ 
| 12 | 9  | 3  | #text  | 10 | Free text    | 
+----+----------+----------+--------------+------+--------------------------+ 

的id显示清楚，算法是宽度第一，没有id=1（为什么ev呃）和nodetype允许区分元素，属性和（浮动）文本。 prev专栏指向连锁店中的兄弟姐妹。缺少的列都与命名空间...

与FROM OPENXML的做法已经过时了，但是这是罕见的情况下，它可能仍然是非常有用的一个...

你得到ID和ParentIDs列表你可能会查询一个递归CTE ...这取决于你想要做什么与此后...

Answer 2

将XML分解为元素和属性及其路径和父母的脚本。从http://beyondrelational.com/modules/2/blogs/28/posts/10495/xquery-lab-58-select-from-xml.aspx

CREATE FUNCTION [dbo].[XMLTable]( 
    @x XML 
) 
RETURNS TABLE 
AS RETURN 
/*---------------------------------------------------------------------- 
This INLINE TVF uses a recursive CTE that processes each element and 
attribute of the XML document passed in. 
----------------------------------------------------------------------*/ 
WITH cte AS ( 
    /*------------------------------------------------------------------ 
    Anchor part of the recursive query. Retrieves the root element 
    of the XML document 
    ------------------------------------------------------------------*/ 
    SELECT 
     1 AS lvl, 
     x.value('local-name(.)','NVARCHAR(MAX)') AS Name, 
     CAST(NULL AS NVARCHAR(MAX)) AS ParentName, 
     CAST(1 AS INT) AS ParentPosition, 
     CAST(N'Element' AS NVARCHAR(20)) AS NodeType, 
     x.value('local-name(.)','NVARCHAR(MAX)') AS FullPath, 
     x.value('local-name(.)','NVARCHAR(MAX)') 
      + N'[' 
      + CAST(ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS NVARCHAR) 
      + N']' AS XPath, 
     ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS Position, 
     x.value('local-name(.)','NVARCHAR(MAX)') AS Tree, 
     x.value('text()[1]','NVARCHAR(MAX)') AS Value, 
     x.query('.') AS this,   
     x.query('*') AS t, 
     CAST(CAST(1 AS VARBINARY(4)) AS VARBINARY(MAX)) AS Sort, 
     CAST(1 AS INT) AS ID 
    FROM @x.nodes('/*') a(x) 
    UNION ALL 
    /*------------------------------------------------------------------ 
    Start recursion. Retrieve each child element of the parent node 
    ------------------------------------------------------------------*/ 
    SELECT 
     p.lvl + 1 AS lvl, 
     c.value('local-name(.)','NVARCHAR(MAX)') AS Name, 
     CAST(p.Name AS NVARCHAR(MAX)) AS ParentName, 
     CAST(p.Position AS INT) AS ParentPosition, 
     CAST(N'Element' AS NVARCHAR(20)) AS NodeType, 
     CAST( 
      p.FullPath 
      + N'/' 
      + c.value('local-name(.)','NVARCHAR(MAX)') AS NVARCHAR(MAX) 
     ) AS FullPath, 
     CAST( 
      p.XPath 
      + N'/' 
      + c.value('local-name(.)','NVARCHAR(MAX)') 
      + N'[' 
      + CAST(ROW_NUMBER() OVER(
       PARTITION BY c.value('local-name(.)','NVARCHAR(MAX)') 
       ORDER BY (SELECT 1)) AS NVARCHAR ) 
      + N']' AS NVARCHAR(MAX) 
     ) AS XPath, 
     ROW_NUMBER() OVER(
       PARTITION BY c.value('local-name(.)','NVARCHAR(MAX)') 
       ORDER BY (SELECT 1)) AS Position, 
     CAST( 
      SPACE(2 * p.lvl - 1) + N'|' + REPLICATE(N'-', 1) 
      + c.value('local-name(.)','NVARCHAR(MAX)') AS NVARCHAR(MAX) 
     ) AS Tree, 
     CAST(c.value('text()[1]','NVARCHAR(MAX)') AS NVARCHAR(MAX)) AS Value, 
     c.query('.') AS this,   
     c.query('*') AS t, 
     CAST( 
      p.Sort 
      + CAST((lvl + 1) * 1024 
      + (ROW_NUMBER() OVER(ORDER BY (SELECT 1)) * 2) AS VARBINARY(4) 
     ) AS VARBINARY(MAX)) AS Sort, 
     CAST( 
      (lvl + 1) * 1024 
      + (ROW_NUMBER() OVER(ORDER BY (SELECT 1)) * 2) AS INT 
     ) 
    FROM cte p 
    CROSS APPLY p.t.nodes('*') b(c)   
), cte2 AS ( 
    SELECT 
     lvl AS Depth, 
     Name AS NodeName, 
     ParentName, 
     ParentPosition, 
     NodeType, 
     FullPath, 
     XPath, 
     Position, 
     Tree AS TreeView, 
     Value, 
     this AS XMLData, 
     Sort, ID 
    FROM cte 
    UNION ALL 
    /*------------------------------------------------------------------ 
    Attributes do not need recursive calls. So add the attributes 
    to the query output at the end. 
    ------------------------------------------------------------------*/ 
    SELECT 
     p.lvl, 
     x.value('local-name(.)','NVARCHAR(MAX)'), 
     p.Name, 
     p.Position, 
     CAST(N'Attribute' AS NVARCHAR(20)), 
     p.FullPath + N'/@' + x.value('local-name(.)','NVARCHAR(MAX)'), 
     p.XPath + N'/@' + x.value('local-name(.)','NVARCHAR(MAX)'), 
     1, 
     SPACE(2 * p.lvl - 1) + N'|' + REPLICATE('-', 1) 
      + N'@' + x.value('local-name(.)','NVARCHAR(MAX)'), 
     x.value('.','NVARCHAR(MAX)'), 
     NULL, 
     p.Sort, 
     p.ID + 1 
    FROM cte p 
    CROSS APPLY this.nodes('/*/@*') a(x) 
) 
SELECT 
    ROW_NUMBER() OVER(ORDER BY Sort, ID) AS ID, 
    ParentName, ParentPosition,Depth, NodeName, Position, 
    NodeType, FullPath, XPath, TreeView, Value, XMLData 
FROM cte2; 
go 
SELECT * FROM dbo.XMLTable(' 
<employees> 
    <emp name="jacob"/> 
    <emp name="steve"> 
     <phone>123</phone> 
    some text      
    </emp> 
</employees> 
')