上一节中，我们介绍了一些xml的xpath属性和函数

下面我们来介绍两个比较特殊的使用：

1.获取相同节点的最大值

2.获取相同节点某属性最大值

xmlName为“内容”

1.获取相同节点的最大值

     string fileName = HttpContext.Current.Request.PhysicalApplicationPath + "\\Xml\\" + xmlName + ".xml";//xml的物理路径
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(fileName);
      
            XmlNode fdfdf = xmlDoc.SelectSingleNode("//rows[not(.<//rows)]");

   string fileName = HttpContext.Current.Request.PhysicalApplicationPath + "\\Xml\\" + xmlName + ".xml";//xml的物理路径
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(fileName);
            XmlNode maxNodejj = xmlDoc.SelectSingleNode("//rows/@ID[not(.<//rows/@ID)]");

<?xml version="1.0" encoding="utf-8"?>
<config>
  <Header ID="ID" class="class" class_name="class_name" year="year" school="school" count="count">2
  </Header>
  <rows ID="01" class="一五班" class_name="实验班" year="2013" school="三峡高级中学" count="30">4
  </rows>
  <rows ID="02" class="一六班" class_name="奥数班" year="2013" school="三峡高级中学" count="25">9
  </rows>
  <rows ID="03" class="一七班" class_name="阳光班" year="2013" school="三峡高级中学" count="69">8
  </rows>
</config>