运用LINQ

LINQ TO XML

<?xml version="1.0"?>
<configuration>
  <account>
    <type name="xxxxx">
      <target>client</target>
      <from display="xxxxx">xxxx@xxx.com</from>
      <to>xxxx@xxx.com</to>
      <cc></cc>
     </type>
    <type name="xxxx">
      <target>client</target>
      <from>xxxxx@xxx.com</from>
      <to>xxxxx@xxx.com</to>
      <cc></cc>
     </type>
  </account>

<configuration>

    string path = Path.Combine(serverMap, "Config\\EmailAccount.xml");
    XDocument xdoc = XDocument.Parse(File.ReadAllText(path));

    var account = from c in xdoc.Descendants("account").Descendants("type")
                          where c.Attribute("name").Value == type
                          select new
                          {
                              Type=c.Attribute("name").Value,
                              Target = c.Descendants("target").First().Value,
                              From = c.Descendants("from").First().Value,
                              FromDisplay = c.Descendants("from").Attributes("display").Count()==0
                                                                        ?c.Descendants("from").First().Value:c.Descendants("from").Attributes("display").FirstOrDefault().Value,
                              To = c.Descendants("to").First().Value,
                              Cc = c.Descendants("cc").First().Value
                          };

 

 

LINQ TO DataTable

            DataTable dt=new DataTable();

            dt.Columns.Add("SerialNumber");
            dt.Columns.Add("CreateTime");
            dt.Columns.Add("A");
            dt.Columns.Add("B");
            dt.Columns.Add("C");

            DataRow dn=dt.NewRow();

            dn[0] = "xxxx65";
            dn[1]="1999-1-1";
            dn[2]=0;
            dn[3]=0;
            dn[4]=0;

            dt.Rows.Add(dn);

            dn=dt.NewRow();

            dn[0] = "xxxx40";
            dn[1]="1999-1-1";
            dn[2]=0;
            dn[3]=0;
            dn[4]=0;

            dt.Rows.Add(dn);

            dn=dt.NewRow();

            dn[0] = "xxxx65";
            dn[1]="1999-1-2";
            dn[2]=0;
            dn[3]=0;
            dn[4]=0;

            dt.Rows.Add(dn);

            //var ss = from c in dt.AsEnumerable() 
            //         group c by new {
            //             A=c.Field<string>("CreateTime"),
            //             B = c.Field<string>("SerialNumber")
            //         } 
            //         into g 
            //         select new { g.Key,Count=g.Count(),g };

            var serialNumbers = new List<string> { "xxxx40", "xxxx65" };

            var ss = from c in dt.AsEnumerable()
                     group c by
                         c.Field<string>("CreateTime")
                         into g
                         where g.Count() != serialNumbers.Count()
                         select new
                         {
                             g.Key,
                             InsertSerialNumber = string.Join(",", serialNumbers.Except(g.Select(n => n.Field<string>("SerialNumber"))).ToArray())
                         };


            foreach(var s in ss)
            {
                foreach (var item in s.InsertSerialNumber.Split(','))
                {
                    DataRow insert = dt.NewRow();

                    insert[0] = item;
                    insert[1] = s.Key;
                    insert[2] = 0;
                    insert[3] = 0;
                    insert[4] = 0;

                    dt.Rows.Add(insert);
                }
            }
        }