LINQ简单案例

1.在visual studio 创建一个解决方案，新建一个控制台程序Kong

2.新建两个类，分别为Master 类和Kongfu类  Master类中包含成员如下，并重写ToString方法

namespace linQ
{
    class Master
    {
        public int id;
        public string name;//什么人
        public string kongfu;//什么功夫
        public int level;//武学等级

        public override string ToString()
        {
            return "序号" + id +"  "+ "名字" + name +"  " +"功夫" + kongfu +"   " +"武学等级" + level;
        }
    }
}
Kongfu类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace linQ
{
    class Kongfu
    {
        public int id;//武学ID
        public string name;//武学名称
        public int power;//伤害

        public override string ToString()
        {
            return "ID为" + id + "名字" + name + "伤害" + power;
        }
    }
}

Main方法中进行查询

using System;
using System.Collections.Generic;
using System.ComponentModel.Design;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace linQ
{
    class Program
    {
        static void Main(string[] args)
        {
            //创建一个LIST列表，并插入数据
            List<Master> master=new List<Master>()
            {
                new Master(){id=1,kongfu="葵花宝典",level =10,name = "东方不败"},
                new Master(){id=2,kongfu="独孤九剑",level = 4,name ="令狐冲"},
                new Master(){id=3,kongfu ="辟邪剑谱",level = 2,name="林平之"},
                new Master(){id=4,kongfu="葵花宝典",level =8,name="岳不群"}

               };
            List<Kongfu> kongfu=new List<Kongfu>()
            {
                new Kongfu(){id=1,name ="葵花宝典",power =300},
                new Kongfu(){id=2,name = "独孤九剑",power = 200},
                new Kongfu(){id=3,name = "辟邪剑谱",power = 150}

            };
            //LINQ方法查询数据 
            /*var res = from m in master
                where m.level > 8//查询武学等级大于8的人的相关数据
                select m;*/
            //如果查询两个表相关的数据
          //  var res = from master1 in master
             //   from kongfu1 in kongfu
                //查询等级大于4并且上大于武学伤害大于200的相关数据
               // where master1.level > 4 && kongfu1.power > 200
                //select new {a=master1,b=kongfu1};
                //select master1.name;//只输出修炼人的名称

            //如果要对结果根据等级进行排序,查询修炼葵花宝典的人，并进行等级排序
            /*var res1 = from m in master
                from n in kongfu
                where m.kongfu == "葵花宝典"
                orderby m.level 
                select m;*/
            //如果用Join on方法进行连接,根据两个类中的武学进行连接
            var res2 = from m in master
                join n in kongfu on m.kongfu equals n.name
                where m.level > 8
                select m.name;
            
            
                       
            //用循环遍历输出显示想要查询的结果
            foreach (var a in res2)
            {
                Console.WriteLine(a);
            }
            Console.ReadKey();
        }
    }
}