SQL Server 操作XML数据

1.xml.exist
   输入为XQuery表达式，返回0，1或是Null。0表示不存在，1表示存在，Null表示输入为空
2.xml.value
   输入为XQuery表达式，返回一个SQL Server标量值
3.xml.query
   输入为XQuery表达式，返回一个SQL Server XML类型流
4.xml.nodes
   输入为XQuery表达式，返回一个XML格式文档的一列行集
5.xml.modify
   使用XQuery表达式对XML的节点进行insert , update 和 delete 操作。

---

下面通过例子对上面的五种操作进行说明：
declare @XMLVar xml = '
<catalog>
       <book category="ITPro">
              <title>Windows Step By Step</title>
              <author>Bill Zack</author>
              <price>49.99</price>
       </book>
       <book category="Developer">
              <title>Developing ADO .NET</title>
              <author>Andrew Brust</author>
              <price>39.93</price>
       </book>
       <book category="ITPro">
              <title>Windows Cluster Server</title>
              <author>Stephen Forte</author>
              <price>59.99</price>
       </book>
</catalog>'

1. xml.exist
   select @XMLVar.exist('/catalog/book')-----返回1
   select @XMLVar.exist('/catalog/book/@category')-----返回1
   select @XMLVar.exist('/catalog/book1')-----返回0
   set @XMLVar = null
   select @XMLVar.exist('/catalog/book')-----返回null

2.xml.value
   select @XMLVar.value('/catalog[1]/book[1]','varchar(MAX)')
   select @XMLVar.value('/catalog[1]/book[2]/@category','varchar(MAX)')
   select @XMLVar.value('/catalog[2]/book[1]','varchar(MAX)')
   结果集为：
   Windows Step By StepBill Zack49.99   Developer   NULL

3.xml.query
   select @XMLVar.query('/catalog[1]/book')
   select @XMLVar.query('/catalog[1]/book[1]')
   select @XMLVar.query('/catalog[1]/book[2]/author')
   结果集分别为：
<book category="ITPro">
  <title>Windows Step By Step</title>
  <author>Bill Zack</author>
  <price>49.99</price>
</book>
<book category="Developer">
  <title>Developing ADO .NET</title>
  <author>Andrew Brust</author>
  <price>39.93</price>
</book>
<book category="ITPro">
  <title>Windows Cluster Server</title>
  <author>Stephen Forte</author>
  <price>59.99</price>
</book>
<book category="ITPro">
  <title>Windows Step By Step</title>
  <author>Bill Zack</author>
  <price>49.99</price>
</book>
<author>Andrew Brust</author>

4.xml.nodes
   select T.c.query('.') as result from @XMLVar.nodes('/catalog/book') as T(c)
   select T.c.query('title') as result from @XMLVar.nodes('/catalog/book') as T(c)
   结果集分别为：
<book category="ITPro"><title>Windows Step By Step</title><author>Bill …………
<book category="Developer"><title>Developing ADO .NET</title><author>Andrew …………
<book category="ITPro"><title>Windows Cluster Server</title><author>Stephen …………
<title>Windows Step By Step</title>
<title>Developing ADO .NET</title>
<title>Windows Cluster Server</title>

 5.xml.modify
SQL Server 2005/2008增加了对XML数据的支持，同时也新增了几种操作XML的方法，本文主要以SQL Server 2008为例介绍如何对XML数据进行insert、update、delete。
SQL Server中新增加了XML.Modify()方法，分别为xml.modify(insert),xml.modify(delete),xml.modify(replace)对应XML的插入，删除和修改操作。
本文以下面XML为例，对三种DML进行说明：
declare @XMLVar xml = '
<catalog>
  <book category="ITPro">
    <title>Windows Step By Step</title>
    <author>Bill Zack</author>
    <price>49.99</price>
  </book>
  <book category="Developer">
    <title>Developing ADO .NET</title>
    <author>Andrew Brust</author>
    <price>39.93</price>
  </book>
  <book category="ITPro">
    <title>Windows Cluster Server</title>
    <author>Stephen Forte</author>
    <price>59.99</price>
  </book>
</catalog>
'

1.XML.Modify(Insert)语句介绍
A.利用as first,at last,before,after四个参数将元素插入指定的位置
set @XMLVar.modify('insert <first name="at first" /> as first into (/catalog[1]/book[1])')
set @XMLVar.modify('insert <last name="at last"/> as last into (/catalog[1]/book[1])')
set @XMLVar.modify('insert <before name="before"/> before (/catalog[1]/book[1]/author[1])')
set @XMLVar.modify('insert <after name="after"/> after (/catalog[1]/book[1]/author[1])')
SELECT @XMLVar.query('/catalog[1]/book[1]');
结果集为：
   1:  <book category="ITPro">
   2:    <first name="at first" />
   3:    <title>Windows Step By Step</title>
   4:    <before name="before" />
   5:    <author>Bill Zack</author>
   6:    <after name="after" />
   7:    <price>49.99</price>
   8:    <last name="at last" />
   9:  </book>

B.将多个元素插入文档中
--方法一：利用变量进行插入
DECLARE @newFeatures xml;
SET @newFeatures = N';
<first>one element</first>
<second>second element</second>'
SET @XMLVar.modify('           )
insert sql:variable("@newFeatures")
into (/catalog[1]/book[1])'
--方法二：直接插入
set @XMLVar.modify(')
insert (<first>one element</first>,<second>second element</second>)
into (/catalog[1]/book[1]/author[1])'
SELECT @XMLVar.query('/catalog[1]/book[1]');

结果集为：

   1:  <book category="ITPro">
   2:    <title>Windows Step By Step</title>
   3:    <author>Bill Zack
   4:      <first>one element</first>
   5:      <second>second element</second>
   6:    </author>
   7:    <price>49.99</price>
   8:    <first>one element</first>
   9:    <second>second element</second>
  10:  </book>

C.将属性插入文档中
--使用变量插入
declare @var nvarchar(10) = '变量插入'
set @XMLVar.modify(
'insert (attribute var {sql:variable("@var")}))
into (/catalog[1]/book[1])'
--直接插入
set @XMLVar.modify(
'insert (attribute name {"直接插入"}))
into (/catalog[1]/book[1]/title[1])'
--多值插入
set @XMLVar.modify(
'insert (attribute Id {"多值插入1"},attribute name {"多值插入2"}) )
into (/catalog[1]/book[1]/author[1])'
SELECT @XMLVar.query('/catalog[1]/book[1]');

结果集为：
   1:  <book category="ITPro" var="变量插入">
   2:    <title name="直接插入">Windows Step By Step</title>
   3:    <author Id="多值插入1" name="多值插入2">Bill Zack</author>
   4:    <price>49.99</price>
   5:  </book>

D.插入文本节点
set @XMLVar.modify(
'insert text{"at first"} as first)
into (/catalog[1]/book[1])'
SELECT @XMLVar.query('/catalog[1]/book[1]');

结果集为：
   1:  <book category="ITPro">
   2:    at first
   3:    <title>Windows Step By Step</title>
   4:    <author>Bill Zack</author>
   5:    <price>49.99</price>
   6:  </book>

注意：插入本文同样具体 as first，as last，before，after四种选项，可以参考A中的使用方法

E.插入注释节点
set @XMLVar.modify(
'insert <!--插入评论-->)
before (/catalog[1]/book[1]/title[1])'
SELECT @XMLVar.query('/catalog[1]/book[1]');

结果集为：
   1:  <book category="ITPro">
   2:    <!--插入评论-->
   3:    <title>Windows Step By Step</title>
   4:    <author>Bill Zack</author>
   5:    <price>49.99</price>
   6:  </book>
注意插入注释节点同样具体 as first，as last，before，after四种选项，可以参考A中的使用方法

F.插入处理指令
set @XMLVar.modify(
'insert <?Program "Instructions.exe" ?>)
before (/catalog[1]/book[1]/title[1])'
SELECT @XMLVar.query('/catalog[1]/book[1]');
结果集为：
   1:  <book category="ITPro">
   2:    <?Program "Instructions.exe" ?>
   3:    <title>Windows Step By Step</title>
   4:    <author>Bill Zack</author>
   5:    <price>49.99</price>
   6:  </book>
注意插入处理指令同样具体 as first，as last，before，after四种选项，可以参考A中的使用方法

G.根据 if 条件语句进行插入
set @XMLVar.modify(
'insert )
if (/catalog[1]/book[1]/title[2]) then
    text{"this is a 1 step"}
else ( text{"this is a 2 step"} )
    into (/catalog[1]/book[1]/price[1])'
SELECT @XMLVar.query('/catalog[1]/book[1]');
结果集为：
   1:  <book category="ITPro">
   2:    <title>Windows Step By Step</title>
   3:    <author>Bill Zack</author>
   4:    <price>49.99this is a 2 step</price>
   5:  </book>

2.XML.Modify(delete)语句介绍
--删除属性
set @XMLVar.modify('delete /catalog[1]/book[1]/@category')
--删除节点
set @XMLVar.modify('delete /catalog[1]/book[1]/title[1]')
--删除内容
set @XMLVar.modify('delete /catalog[1]/book[1]/author[1]/text()')
--全部删除
set @XMLVar.modify('delete /catalog[1]/book[2]')

SELECT @XMLVar.query('/catalog[1]');

结果集为：
   1:  <catalog>
   2:    <book>
   3:      <author />
   4:      <price>49.99</price>
   5:    </book>
   6:    <book category="ITPro">
   7:      <title>Windows Cluster Server</title>
   8:      <author>Stephen Forte</author>
   9:      <price>59.99</price>
  10:    </book>
  11:  </catalog>

3.XML.Modify(replace)语句介绍
--替换属性
set @XMLVar.modify('replace value of(/catalog[1]/book[1]/@category)) with ("替换属性")'
--替换内容
set @XMLVar.modify('replace value of(/catalog[1]/book[1]/author[1]/text()[1])) with("替换内容")'
--条件替换
set @XMLVar.modify('replace value of (/catalog[1]/book[2]/@category))
with(
if(count(/catalog[1]/book)>4) then
    "条件替换1"
else
    "条件替换2")'

SELECT @XMLVar.query('/catalog[1]');

结果集为：
   1:  <catalog>
   2:    <book category="替换属性">
   3:      <title>Windows Step By Step</title>
   4:      <author>替换内容</author>
   5:      <price>49.99</price>
   6:    </book>
   7:    <book category="条件替换2">
   8:      <title>Developing ADO .NET</title>
   9:      <author>Andrew Brust</author>
  10:      <price>39.93</price>
  11:    </book>
  12:    <book category="ITPro">
  13:      <title>Windows Cluster Server</title>
  14:      <author>Stephen Forte</author>
  15:      <price>59.99</price>
  16:    </book>
  17:  </catalog>

---

示例1：从XML中解析数据到表变量

DECLARE @ItemMessage XML 
DECLARE @ItemTable TABLE(ItemNumber INT PRIMARY KEY,ItemDescription NVARCHAR(300))
SET @ItemMessage=N'<ItemList> 
<Item> 
    <ItemNumber>1</ItemNumber> 
    <ItemDescription>XBox 360,超值</ItemDescription> 
</Item> 
<Item> 
    <ItemNumber>2</ItemNumber> 
    <ItemDescription>Windows Phone7,快来尝鲜吧</ItemDescription> 
</Item> 
</ItemList>'
INSERT INTO @ItemTable 
( 
ItemNumber, 
ItemDescription 
) 
SELECT T.c.value('(ItemNumber/text())[1]','INT'), 
T.c.value('(ItemDescription/text())[1]','NVARCHAR(300)') 
FROM @ItemMessage.nodes('/ItemList/Item') AS T(c)
SELECT ItemNumber, 
ItemDescription 
FROM @ItemTable

运行结果：

示例二： 解析带命名空间的XML数据

DECLARE @ItemMessage XML
DECLARE @ItemTable TABLE(ItemNumber INT PRIMARY KEY,ItemDescription NVARCHAR(300))
--包含 XML 命名空间
SET @ItemMessage=N'<ItemList xmlns="http://cd.love.com/SOA">
<Item>
    <ItemNumber>1</ItemNumber>
    <ItemDescription>XBox 360,超值</ItemDescription>
</Item>
<Item>
    <ItemNumber>2</ItemNumber>
    <ItemDescription>Windows Phone7,快来尝鲜吧</ItemDescription>
</Item>
</ItemList>'
--设置命名空间
;WITH XMLNAMESPACES(DEFAULT 'http://cd.love.com/SOA')
INSERT INTO @ItemTable
(
ItemNumber,
ItemDescription
)
SELECT T.c.value('(ItemNumber/text())[1]','INT'),
T.c.value('(ItemDescription/text())[1]','NVARCHAR(300)')
FROM @ItemMessage.nodes('/ItemList/Item') AS T(c)
SELECT ItemNumber,
ItemDescription
FROM @ItemTable

运行结果：

---

示例三：将 xml tag标签的中值 转为 table 格式

DECLARE @xml xml='<mssql version="10.50.4000" name="Microsoft SQL Server Developer Edition (64-bit)">
  <type name="Windows 7 Main Server">
    <tag KeyValue="enabled">
      <boolean>true</boolean>
    </tag>
    <tag KeyValue="disabled">
      <tag method="Read">
        <type name="Windows 8 virtual pc">
          <tag KeyValue="uniqueKey">
            <string>SQL Server 2008</string>
          </tag>
          <tag KeyValue="value 8GB">
            <string>SQL Server 2000</string>
          </tag>
        </type>
      </tag>
      <tag method="Read">
        <type name="Windows 8 virtual pc">
          <tag KeyValue="primaryKey">
            <string>SQL Server 2008 R2 SP1</string>
          </tag>
          <tag KeyValue="value 8GB">
            <string>SQL Server 2005 SP3</string>
          </tag>
        </type>
      </tag>
      <tag method="Write">
        <type name="Windows Server 2008 virtual pc">
          <tag KeyValue="primaryKey">
            <string>SQL Server 2008 R2 SP2</string>
          </tag>
          <tag KeyValue="value 10GB">
            <string>SQL Server 2012</string>
          </tag>
        </type>
      </tag>
    </tag>
  </type>
</mssql>';

SELECT    b.c.value('@version', 'varchar(100)') [version]
        ,b.c.value('@name', 'varchar(200)') [Name]
        ,f.c.value('@name', 'varchar(200)') [ServerName]
        ,r.c.value('@KeyValue', 'varchar(50)') [KeyValue]
        ,r.c.value('(boolean)[1]', 'varchar(25)') [boolean]
        ,k.c.value('@method', 'varchar(25)') [method]
        ,k.c.value('@name', 'varchar(25)') [virtual_pc]
        ,y.c.value('@KeyValue', 'varchar(25)') [KeyValue]
        ,y.c.value('(string)[1]', 'varchar(25)') [string]
FROM @xml.nodes('mssql') b(c)
        CROSS APPLY b.c.nodes('type')  f(c)
            CROSS APPLY f.c.nodes('tag')  r(c)
                CROSS APPLY f.c.nodes('tag/tag')  k(c)
                        CROSS APPLY f.c.nodes('tag/tag/type/tag')  y(c);