sqlserver 操作xml

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>