C#_LINQ數據查詢

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace CShapeTest
{
    class Master
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        public string Kungfu { get; set; }
        public int Level { get; set; }

        public override string ToString()
        {
            return string.Format("Id:{0}, Name:{1}, Age:{2}, Kungfu:{3}, Level:{4}", Id, Name, Age, Kungfu, Level);
        }
    }

    class Kungfu
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Power { get; set; }

        public override string ToString()
        {
            return string.Format("Id:{0}, Name:{1}, Power:{2}", Id, Name, Power);
        }
    }

    class Start
    {
        static void Main(string[] args)
        {
            List<Master> masterList = new List<Master>();
            masterList.Add(new Master() { Id = 1, Name = "東風不敗", Age = 35, Kungfu = "葵花寶典", Level = 10});
            masterList.Add(new Master() { Id = 2, Name = "林平之", Age = 23, Kungfu = "葵花寶典", Level = 7 });
            masterList.Add(new Master() { Id = 3, Name = "嶽不羣", Age = 50, Kungfu = "葵花寶典", Level = 8 });
            masterList.Add(new Master() { Id = 4, Name = "令狐沖", Age = 23, Kungfu = "孤獨九劍", Level = 10 });
            masterList.Add(new Master() { Id = 5, Name = "梅超風", Age = 35, Kungfu = "九陰真經", Level = 8 });
            masterList.Add(new Master() { Id = 6, Name = "黃藥師", Age = 50, Kungfu = "彈指神通", Level = 10 });
            masterList.Add(new Master() { Id = 7, Name = "風清揚", Age = 50, Kungfu = "孤獨九劍", Level = 10 });

            List<Kungfu> kungfuList = new List<Kungfu>();
            kungfuList.Add(new Kungfu() { Id = 1, Name = "打狗棒法", Power = 90});
            kungfuList.Add(new Kungfu() { Id = 2, Name = "降龍十八掌", Power = 95 });
            kungfuList.Add(new Kungfu() { Id = 3, Name = "葵花寶典", Power = 100 });
            kungfuList.Add(new Kungfu() { Id = 4, Name = "孤獨九劍", Power = 100 });
            kungfuList.Add(new Kungfu() { Id = 5, Name = "九陰真經", Power = 100 });
            kungfuList.Add(new Kungfu() { Id = 6, Name = "彈指神通", Power = 100 });

            // 查詢武功等級大於8的大師

            // 使用foreach查詢
            //List<Master> resList = new List<Master>();
            //foreach (var item in masterList)
            //{
            //    if (item.Level > 8)
            //    {
            //        resList.Add(item);
            //    }
            //}

            //foreach (var item in resList)
            //{
            //    Console.WriteLine(item);
            //}

            // 使用LINQ單一查詢(表達式寫法)
            //var resList = from m in masterList where m.Level > 8 && m.Age > 23 select m;
            //foreach (var item in resList)
            //{
            //    Console.WriteLine(item);
            //}

            // 使用LINQ單一查詢(擴展方法寫法)
            //var resList = masterList.Where((Master m) =>
            //{
            //    if (m.Level > 8 && m.Age > 23)
            //    {
            //        return true;
            //    }
            //    else
            //    {
            //        return false;
            //    }
            //});
            //foreach (var item in resList)
            //{
            //    Console.WriteLine(item);
            //}

            // 查詢武功殺傷力大於90，並且年齡小於30的大師

            // 使用LINQ聯合查詢(表達式寫法)
            //var resList = from m in masterList from k in kungfuList where m.Kungfu == k.Name && m.Age < 30 && k.Power > 90 select m;
            //foreach (var item in resList)
            //{
            //    Console.WriteLine(item);
            //}

            // 使用LINQ聯合查詢(擴展方法寫法)
            //var resList = masterList.SelectMany((Master m) => kungfuList, (Master m, Kungfu k) => new {master = m, kungfu = k}).Where((x) => x.master.Kungfu == x.kungfu.Name && x.master.Age < 30 && x.kungfu.Power > 90);
            //foreach (var item in resList)
            //{
            //    Console.WriteLine(item);
            //}

            //// 使用LINQ單一查詢的同時，進行排序(表達式寫法)
            //var resList = from m in masterList where m.Level > 8 orderby m.Age,m.Level select m;
            //foreach (var item in resList)
            //{
            //    Console.WriteLine(item);
            //}

            // 使用LINQ單一查詢的同時，進行排序(擴展方法寫法)
            var resList = masterList.Where(m => m.Level > 8).OrderBy(m => m.Age).ThenBy(m => m.Level);
            foreach (var item in resList)
            {
                Console.WriteLine(item);
            }

            Console.ReadLine();
        }
    }
}