sql xml入门:xpath和xquery_sqlserver

/*
sql xml 入门:
    –by jinjazz
    –http://blog.csdn.net/jinjazz
   
    1、xml:        能认识元素、属性和值

   
    2、xpath:    寻址语言，类似windows目录的查找(没用过dir命令的话就去面壁)
               
                语法格式，这些语法可以组合为条件：
                "."表示自己，".."表示父亲，"/"表示儿子，"//"表示后代，
                "name"表示按名字查找，"@name"表示按属性查找
               
                "集合[条件]" 表示根据条件取集合的子集，条件可以是
                    数  值：数字,last(),last()-数字 等
                    布尔值：position()<数字,@name=’条件’,name=’条件’
                条件是布尔值的时候可以合并计算：and or
   
    3、xquery:    基于xpath标的准查询语言，sqlserver xquery包含如下函数
                exist(xpath条件)：返回布尔值表示节点是否存在
                query(xpath条件)：返回由符合条件的节点组成的新的xml文档
                value(xpath条件,数据类型)：返回指定的标量值，xpath条件结果必须唯一
                nodes(xpath条件): 返回由符合条件的节点组成的一行一列的结果表
*/

declare @ data xml
set @ data = ‘
<bookstore>
<book category="COOKING">
  <title lang="en">Everyday Italian</title>
  <author>Giada De Laurentiis</author>
  <year>2005</year>
  <price>30.00</price>
</book>
<book category="CHILDREN">
  <title lang="jp">Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>
<book category="web">
  <title lang="en">XQuery Kick Start</title>
  <author>James McGovern</author>
  <author>Per Bothner</author>
  <author>Kurt Cagle</author>
  <author>James Linn</author>
  <author>Vaidyanathan Nagarajan</author>
  <year>2003</year>
  <price>49.99</price>
</book>
<book category="WEB">
  <title lang="cn">Learning XML</title>
  <author>Erik T. Ray</author>
  <year>2003</year>
  <price>39.95</price>
</book>
</bookstore>
‘

–测试语句，如果不理解语法请参考上面的xpath规则和xquery函数说明

–1、文档
select @ data
–2、任意级别是否存在price节点
select @ data . exist (‘//price’ )
–3、获取所有book节点
select @ data . query (‘//book’ )
–4、获取所有包含lang属性的节点
select @ data . query (‘//*[@lang]’ )
–5、获取第一个book节点
select @ data . query (‘//book[1]’ )
–6、获取前两个book节点
select @ data . query (‘//book[position()<=2]’ )
–7、获取最后一个book节点
select @ data . query (‘//book[last()]’ )
–8、获取price>35的所有book节点
select @ data . query (‘//book[price>35]’ )
–9、获取category="WEB"的所有book节点
select @ data . query (‘//book[@category="WEB"]’ )
–10、获取title的lang="en"的所有book节点
select @ data . query (‘//book/title[@lang="en"]’ )
–11、获取title的lang="en"且 price>35的所有book节点
select @ data . query (‘//book[./title[@lang="en"] or price>35 ]’ )
–12、获取title的lang="en"且 price>35的第一book的(第一个)title
select @ data . query (‘//book[./title[@lang="en"] and price>35 ]’ ). value (‘(book/title)[1]’ , ‘varchar(max)’ )
–13、等价于10
select @ data . value (‘(//book[./title[@lang="en"] and price>35 ]/title)[1]’ , ‘varchar(max)’ )
–14、获取title的lang="en"且 price>35的第一book的(第一个)title的lang属性
select @ data . value (‘((//book[@category="WEB" and price>35 ]/title)[1]/@lang)[1]’ , ‘varchar(max)’ )
–15、获取第一本书的title
select Tab . Col . value (‘(book/title)[1]’ , ‘varchar(max)’ ) as title
    from @ data . nodes (‘bookstore’ )as Tab (Col )
–16、获取每本书的第一个author
select Tab . Col . value (‘author[1]’ , ‘varchar(max)’ ) as title
    from @ data . nodes (‘//book’ )as Tab (Col )
–17、获取所有book的所有信息
select
T . C . value (‘title[1]’ , ‘varchar(max)’ ) as title ,
T . C . value (‘year[1]’ , ‘int’ ) as year ,
T . C . value (‘title[1]’ , ‘varchar(max)’ )as title ,
T . C . value (‘price[1]’ , ‘float’ ) as price ,
T . C . value (‘author[1]’ , ‘varchar(max)’ ) as author1 ,
T . C . value (‘author[2]’ , ‘varchar(max)’ ) as author2 ,
T . C . value (‘author[3]’ , ‘varchar(max)’ ) as author3 ,
T . C . value (‘author[4]’ , ‘varchar(max)’ ) as author4
from @ data . nodes (‘//book’ ) as T (C )
–18、获取不是日语(lang!="jp")且价格大于35的书的所有信息
select
T . C . value (‘title[1]’ , ‘varchar(max)’ ) as title ,
T . C . value (‘year[1]’ , ‘int’ ) as year ,
T . C . value (‘title[1]’ , ‘varchar(max)’ )as title ,
T . C . value (‘price[1]’ , ‘float’ ) as price ,
T . C . value (‘author[1]’ , ‘varchar(max)’ ) as author1 ,
T . C . value (‘author[2]’ , ‘varchar(max)’ ) as author2 ,
T . C . value (‘author[3]’ , ‘varchar(max)’ ) as author3 ,
T . C . value (‘author[4]’ , ‘varchar(max)’ ) as author4
from @ data . nodes (‘//book[./title[@lang!="jp"] and price>35 ]’ ) as T (C )

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