SQL Server 中对XML数据的五种基本操作

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

关于modify内容，请参见

http://blog.csdn.net/tjvictor/archive/2009/07/21/4368496.aspx

如需转载，请注明本文原创自CSDN TJVictor专栏

http://blog.csdn.net/tjvictor/archive/2009/07/21/4368511.aspx