linq to sql之Distinct

Distict用来排除相同序列中元素的，对于基础类型，可以直接使用Distinct，如：
int[] a = {1, 2, 2, 3, 3, 3, 4};
var reslut = a.Distinct();
结果是1,2,3,4
但对于自定义类型，则需要额外的一些操作，方式有多种，这里选择其中一种，即实现IEquatable<T>，如：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace ConsoleApplication1
{
    class Employee : IEquatable<Employee>
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public bool Equals(Employee other)
        {
            if (Object.ReferenceEquals(other, null))
                return false;
            if (ReferenceEquals(this, other))
                return true;
            return ID.Equals(other.ID);
        }
 
        public override int GetHashCode()
        {
            return ID.GetHashCode();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using SFast;
 
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            //EmpLevelCls cls = ConfigurationManager.GetSection("EmpLevel") as EmpLevelCls;
            //Console.WriteLine(cls.Enterprises[0].id);
 
            List<Employee> employees = new List<Employee>
            {
                new Employee {ID = 1, Name = "Ringgo"},
                new Employee {ID = 2, Name = "Rex"},
                new Employee {ID = 1, Name = "Ringgo"}
            };
            var reslut = employees.Distinct();
 
            Console.WriteLine(reslut._ToJsonStr());
            Console.ReadKey();
        }
    }
}