1 using System;
  2 using System.Collections.Generic;
  3 using System.Data.Entity;
  4 using System.Linq;
  5 using System.Linq.Expressions;
  6 using System.Text;
  7 
  8 namespace EFtest
  9 {
 10     class Program
 11     {
 12         static void Main(string[] args)
 13         {
 14             testEntities context = new testEntities();
 15 
 16             //增
 17             //T_Test t = new T_Test() {Name="小林" };          
 18             //context.T_Test.Add(t);
 19             //context.SaveChanges();
 20 
 21 
 22             //删
 23             //lambda方式
 24             //var t = context.T_Test.Where(u=>(u.Id==1)).FirstOrDefault();
 25 
 26             //linq to sql方式
 27             //var t = (from u in context.T_Test
 28             //         where u.Id == 1
 29             //         select u).FirstOrDefault();
 30             //context.T_Test.Remove(t);
 31             //context.SaveChanges();
 32             //数据的删除用这种方式更方便，效率更高
 33             //T_Test t = new T_Test() { Id=2 };
 34             //context.Entry<T_Test>(t).State=EntityState.Deleted;
 35             //context.SaveChanges();
 36 
 37             //改
 38             //var t = (from u in context.T_Test
 39             //         where u.Id == 2
 40             //         select u).FirstOrDefault();
 41             //t.Name = "小林";
 42             //context.SaveChanges();
 43 
 44             //查
 45             //var t = (from u in context.T_Test
 46             //         where u.Id == 2
 47             //         select u).FirstOrDefault();
 48             //Console.WriteLine(t.Id + t.Name);
 49             
 50             //通用分页
 51             int count;          
 52             GetPageListParameter<T_Test, int> parameter=new GetPageListParameter<T_Test,int>();
 53             parameter.isAsc=true;
 54             parameter.orderByLambda = s => s.Id;
 55             parameter.pageIndex = 1;
 56             parameter.pageSize = 3;
 57             parameter.selectLambda = s => new Person{Name=s.Name };
 58             parameter.whereLambda = s => s.Id > 3;
 59 
 60             var data = GetPageList<T_Test, int>(parameter, out count);
 61 
 62             foreach (Person t in data)
 63             {
 64                 Console.WriteLine(t.Name);
 65             }
 66 
 67             Console.ReadKey();
 68         }
 69 
 70         public static List<dynamic> GetPageList<T, TKey>(GetPageListParameter<T, TKey> parameter, out int count) where T : class
 71         {
 72             testEntities context = new testEntities();
 73             //注意顺序
 74             count = context.Set<T>().Where<T>(parameter.whereLambda).Count();
 75             var list = context.Set<T>().Where<T>(parameter.whereLambda);
 76             if (parameter.isAsc)
 77             {
 78                 list = list.OrderBy(parameter.orderByLambda);
 79             }
 80             else
 81             {
 82                 list = list.OrderByDescending(parameter.orderByLambda);
 83             }
 84 
 85             return list.Skip((parameter.pageIndex - 1) * parameter.pageSize).Take(parameter.pageSize).Select(parameter.selectLambda).ToList();
 86         }
 87     }
 88 
 89     //取所需列
 90     public class Person
 91     {
 92         public string Name { get; set; }
 93     }
 94 
 95     //封装方法参数
 96     public class GetPageListParameter<T, TKey>
 97     {
 98         public Expression<Func<T, dynamic>> selectLambda { get; set; }
 99         public Expression<Func<T, bool>> whereLambda { get; set; }
100         public Expression<Func<T, TKey>> orderByLambda { get; set; }
101         public int pageSize { get; set; }
102         public int pageIndex { get; set; }
103         public bool isAsc { get; set; }
104     }
105 }