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;
SET @XMLVar= '
<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(
N'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(N'replace value of(/catalog[1]/book[1]/@category)
with ("替换属性")' )
--替换内容
set @XMLVar.modify(N'replace value of(/catalog[1]/book[1]/author[1]/text()[1])
with("替换内容")' )
--条件替换
set @XMLVar.modify(N'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>
