SQLServer 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。
狼蚁网站SEO优化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，请参见下一篇文章。