Linq DataTable的修改和查询

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Data;namespace WebApplication_study.Linq{    public partial class LinqStart : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {            DataTable dt = getDataTable.getData();//源数据            //Linq进行普通查询            var q1 = from dt1 in dt.AsEnumerable()//查询                     orderby dt1.Field<int>("ID") descending//排序                     where dt1.Field<int>("ID") > 2 && dt1.Field<int>("ID") < 6//条件                     select dt1;            Response.Write("查询结果为：<br/>");            foreach (var item in q1)//显示查询结果            {                //Response.Write("<br/>" + item.Field<string>("Name"));//两种写法均可                Response.Write("<br/>" + item["Name"]);            }            //查询结果用于新的DT            DataTable newDT = q1.CopyToDataTable<DataRow>();//经查询生成的DT可用于数据绑定            Response.Write("<br/><br/>新的DT的结果为：<br/>");            foreach (var item2 in newDT.AsEnumerable())//显示查询结果            {                Response.Write("<br/>" + item2["Name"]);            }            // 修改查询的结果            Response.Write("<br/>修改查询结果前：<br/>");            var q3 = from dt3 in dt.AsEnumerable()                     select dt3;            foreach (var item in q3)            {                Response.Write("<br/>" + item["ID"] + "   " + item["Name"] + "   " + item["PID"] + "   ");            }            Response.Write("<br/>修改查询结果后：<br/>");            foreach (var items in dt.AsEnumerable())            {                int PID = (int)items["PID"];                items.SetField<int>("PID", PID + 100);            }            foreach (var item in q3)            {                Response.Write("<br/>" + item["ID"] + "   " + item["Name"] + "   " + item["PID"] + "   ");            }            //DataView测试            DataView dvDT = dt.AsDataView();            EnumerableRowCollection<DataRow> quert4 = from dv in dt.AsEnumerable() select dv;            DataView dvDTQ = quert4.AsDataView();                     //linq调用本地方法            //定义本地方法            Response.Write("<br/>linq调用本地方法：<br/>");            int[] num = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };            var query = from i in num where check(i) select i;            foreach (var item in query)            {                Response.Write(item + "   ");            }        }        /// <summary>        /// 本地方法示例        /// </summary>        /// <param name="num"></param>        /// <returns></returns>        public bool check(int num)        {            if (num > 5)                return true;            else                return false;        }    }}

转自：http://www.cnblogs.com/sunxf2011/archive/2011/07/08/2101008.html