LINQ管理查询和Lambda表达式管理查询

• 新建两个类

    internal class MartialArtMaster
    {
        public int ID { get; set; }
        public string Name { get; set; }

        public int Age { get; set; }
        public string Menpai { get; set; }
        public string Kongfu { get; set; }
        public int Level { get; set; }
        public override string ToString()
        {
            return $"ID:{ID},Name:{Name},Age:{Age},Menpai:{Menpai},Kongfu:{Kongfu},Level:{Level}";
        }

    }

   internal class KongFu
    {
        public int ID { get; set; }
        public string? Name { get; set; }
        public int Power { get; set; }

        public override string ToString()
        {
            return $"ID:{ID},name:{Name},power:{Power}";
        }
    }

• 然后去控制台程序中编写语句：

•         static void Main(string[] args)
          {
              List<MartialArtMaster> martialArts = new List<MartialArtMaster>()
              {
                  new MartialArtMaster(){ID=1, Name="郭靖", Age=30, Kongfu="降龙十八掌",  Menpai="丐帮",Level=10 },
                  new MartialArtMaster(){ID=2, Name="黄蓉", Age=30, Kongfu="打狗棒法",  Menpai="丐帮",Level=9 },
                  new MartialArtMaster(){ID=3, Name="洪七公", Age=30, Kongfu="打狗棒法",  Menpai="丐帮",Level=10 },
                  new MartialArtMaster(){ID=4, Name="任我行", Age=30, Kongfu="葵花宝典",  Menpai="明教",Level=1 },
                  new MartialArtMaster(){ID=5, Name="东方不败", Age=30, Kongfu="葵花宝典",  Menpai="明教",Level=10 },
                  new MartialArtMaster(){ID=6, Name="岳不群", Age=30, Kongfu="葵花宝典",  Menpai="华山",Level=7 },
                  new MartialArtMaster(){ID=7, Name="令狐冲", Age=30, Kongfu="独孤九剑",  Menpai="华山",Level=10 },
                   new MartialArtMaster(){ID=8, Name="黄药师", Age=30, Kongfu="弹指神通",  Menpai="桃花岛",Level=10 },
                   new MartialArtMaster(){ID=9, Name="风清扬", Age=30, Kongfu="独孤九剑",  Menpai="华山",Level=10 }
              };
              List<KongFu> kongFu = new List<KongFu>()
              {
                  new KongFu(){ ID=1, Name="降龙十八掌", Power=99},
                  new KongFu(){ ID=2, Name="弹指神通", Power=80},
                  new KongFu(){ ID=3, Name="打狗棒法", Power=90},
                  new KongFu(){ ID=4, Name="葵花宝典", Power=95},
                  new KongFu(){ ID=5, Name="独孤九剑", Power=70}
              };
              Console.WriteLine("----------------------1.分割线(LINQ关联查询)------------------------");
              //LINQ关联查询
              var linqres = from m in martialArts
                            from k in kongFu
                            where m.Kongfu == k.Name && k.Power>90
                            select new { martialArt = m, kongfu = k };
              
              foreach (var item in linqres)
              {
                  Console.WriteLine(item);
              }
              Console.WriteLine("----------------------2.分割线(Lambda表达式查询)------------------------");
              //Lambda表达式查询
              var res= martialArts.SelectMany(t => kongFu, (t, k) => new { martialArt = t, kongfu = k })
                  .Where(x=>x.martialArt.Kongfu==x.kongfu.Name && x.kongfu.Power > 90);
              foreach (var item in res)
              {
                  Console.WriteLine(item);
              }
              Console.WriteLine("----------------------.分割线(LINQ join on集合联合)------------------------");
              //LINQ join on集合联合
              var linqJoin=from m in martialArts
                           join k in kongFu on m.Kongfu equals k.Name
                           where k.Power>90
                           select new { martialArt = m, kongfu = k };
              foreach (var item in linqJoin)
              {
                  Console.WriteLine(item);
              }
  
  
  
          }

   

• 查看结果：