entity sql实例 ef增删改查

1，本篇接着上篇link to sql的实例扩充entity sql.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Linq;
using System.Xml.Linq;
using System.Data.Objects;
using System.Data.Common;

namespace Console1
{
    class Program
    {
        static void Main(string[] args)
        {

            //创建数据库实体
            using (studentEntities stuEntity = new studentEntities())
            {
                #region Execute方法
                //string esql = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query = stuEntity.CreateQuery<T_StuInfo>(esql);//创建查询对象
                //foreach (var c in query)
                //{
                //    Console.WriteLine(c.stuid);
                //}
                //ObjectResult<T_StuInfo> results = query.Execute(MergeOption.NoTracking);//执行对象查询
                //Console.WriteLine(results.Count());              
         
                #endregion

                #region GetResultType方法：返回查询结果的类型信息
                //string esql = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query = stuEntity.CreateQuery<T_StuInfo>(esql);
                //Console.WriteLine(query.GetResultType().ToString());

                #endregion

                #region ToTraceString方法：获取当前执行的SQL语句。
                //string esql = "select value c from studentEntities.T_StuInfo as c";
                //ObjectQuery<T_StuInfo> query1 = stuEntity.CreateQuery<T_StuInfo>(esql);
                ////使用ObjectParameter的写法
                //query1 = query1.Where("it.stuid=@stuid"); //增加参数
                //query1.Parameters.Add(new ObjectParameter("stuid", 4));//为参数赋值
                ////也可以这样写
                //ObjectQuery<T_StuInfo> query2 = stuEntity.T_StuInfo.Where("it.stuid=4");
                //foreach (var c in query1)
                //    Console.WriteLine(c.stuid);
                ////显示查询执行的sql语句
                //Console.WriteLine(query1.ToTraceString());
                //Console.WriteLine(query2.ToTraceString());
               
                #endregion

                #region First/ FirstOrDefault

                //string esql = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query = stuEntity.CreateQuery<T_StuInfo>(esql).Where("it.stuid =4");
                //T_StuInfo stu1 = query.First(); //如果要查询的不存在，异常：序列不包含任何元素
                //T_StuInfo stu2 = query.FirstOrDefault();
                //Console.WriteLine(stu1.stuid);
                //Console.WriteLine(stu2.stuid);
 
                #endregion

                #region Distinct
                //string esql = "select value c.name from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<string> query = stuEntity.CreateQuery<string>(esql);
                //query = query.Distinct();
                //foreach (string c in query)
                //{
                //    Console.WriteLine("姓名:{0}", c);
                //}      

                #endregion

                #region  Except:返回两个查询的差集
                //string esql1 = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query1 = stuEntity.CreateQuery<T_StuInfo>(esql1);
                //string esql2 = "select value c from studentEntities.T_StuInfo as c where c.stuid > 8 order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query2 = stuEntity.CreateQuery<T_StuInfo>(esql2);
                //query1 = query1.Except(query2);//将query1中的query2减去
                //foreach(var c in query1)
                //{
                //    Console.WriteLine("学号:{0},姓名：{1}",c.stuid,c.name);
                //}
                
                #endregion

                #region Intersect：返回两个查询的交集                
                //string esql1 = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query1 = stuEntity.CreateQuery<T_StuInfo>(esql1);
                //string esql2 = "select value c from studentEntities.T_StuInfo as c where c.stuid < 7 order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query2 = stuEntity.CreateQuery<T_StuInfo>(esql2);
                //query1 = query1.Intersect(query2);//创建交集
                //foreach (var c in query1)
                //{
                //    Console.WriteLine(c.name);
                //}

                #endregion

                #region Include:可通过此方法查询出与相关的实体对象
                //Union/UnionAll:返回两个查询的合集，包括重复项。其中UnionAll必须是相同类型或者是可以相互转换的。
                //string esql1 = "select value c from studentEntities.T_StuInfo as c where c.stuid = 4";
                //ObjectQuery<T_StuInfo> query1 = stuEntity.CreateQuery<T_StuInfo>(esql1);
                //query1 = query1.Include("T_Class");//查询结果中包含与之相关的实体对象
                //foreach (T_StuInfo c in query1)
                //{
                //    Console.WriteLine("姓名:{0},班级:{1}", c.name, c.T_Class.name);
                //}
                #endregion

                #region orderby
                //string esql1 = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query1 = stuEntity.CreateQuery<T_StuInfo>(esql1);
                //query1.OrderBy("it.name asc,it.stuid asc");
                ////也可以这样写
                ////query1.OrderBy("it.name desc");
                ////query1.OrderBy("it.stuid asc");
                //foreach (var c in query1)
                //{
                //    Console.WriteLine("姓名:{0},学号：{1}", c.name, c.stuid);
                //}
                #endregion

                #region  Select    SelectValue
                //string esql1 = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
                //ObjectQuery<T_StuInfo> query1 = stuEntity.CreateQuery<T_StuInfo>(esql1);
                //ObjectQuery<DbDataRecord> records = query1.Select("it.stuid,it.name");
                //ObjectQuery<string> records2 = query1.SelectValue<string>("it.name");
                //foreach (string c in records2)
                //{
                //    Console.WriteLine("{0}", c);
                //}
                //Console.WriteLine(records2.ToTraceString());
               
                
                //foreach (DbDataRecord c in records)
                //{
                //    Console.WriteLine("{0},{1}", c[0], c[1]);
                //}
                //Console.WriteLine(records.ToTraceString());

                #endregion

                #region      Skip/Top
                string esql1 = "select value c from studentEntities.T_StuInfo as c order by c.stuid";
                ObjectQuery<T_StuInfo> query1 = stuEntity.CreateQuery<T_StuInfo>(esql1);
                query1 = query1.Skip("it.stuid asc", "2");
                query1 = query1.Top("10");
                foreach (T_StuInfo c in query1)
                {
                    Console.WriteLine("学号:{0},姓名:{1}", c.stuid, c.name);
                }
                Console.WriteLine(query1.ToTraceString());
                //输出结构如下：
                /*
                SELECT TOP (10)
                    [Extent1].[stuid] AS [stuid],
                    [Extent1].[name] AS [name],
                    [Extent1].[phone] AS [phone],
                    [Extent1].[classid] AS [classid]
                    FROM ( 
                 SELECT [Extent1].[stuid] AS [stuid], [Extent1].[name] AS [name], [Extent1
                    ].[phone] AS [phone], [Extent1].[classid] AS [classid], row_number() OVER (ORDER
                     BY [Extent1].[stuid] ASC) AS [row_number]
                            FROM [dbo].[T_StuInfo] AS [Extent1]
                    )  AS [Extent1]
                    WHERE [Extent1].[row_number] > 2
                    ORDER BY [Extent1].[stuid] ASC
                 */
               

                #endregion

                Console.WriteLine("OK");


                Console.Read();
            }
        


        }
     
    }
}

2.下面是ef的增删改查

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Linq;
using System.Xml.Linq;
using System.Data.Objects;
using System.Data.Common;
using System.Data.EntityClient;
using System.Data;
using System.Configuration;

namespace Console1
{
    class Program
    {
        static void Main(string[] args)
        {
            using (studentEntities stuEntity = new studentEntities())
            {
                #region 增加:使用AddTo表(xxx)方法
                //T_StuInfo stu1 = new T_StuInfo { name = "wangjinhe1",phone ="123456",classid = 2 };
                //stuEntity.AddToT_StuInfo(stu1);//直接添加到表对象中
                //int resutl1 = stuEntity.SaveChanges();//保存修改
                //Console.WriteLine(resutl1);

                //T_StuInfo stu2 = stuEntity.T_StuInfo.FirstOrDefault(c => c.name == "wangjinhe1");
                //Console.WriteLine("id:{0},name:{1},phone:{2},classid:{3}", stu2.stuid, stu2.name, stu2.phone, stu2.classid);

                #endregion

                #region 增加：使用ObjectContext的AddObject(string entitySetName, object entity)

                //T_StuInfo stu1 = new T_StuInfo { name = "wangjinhe2",phone ="123456",classid = 2 };
                //stuEntity.AddObject("T_StuInfo", stu1);                
               
                //int resutl1 = stuEntity.SaveChanges();//保存修改
                //Console.WriteLine(resutl1);

                //T_StuInfo stu2 = stuEntity.T_StuInfo.FirstOrDefault(c => c.name == "wangjinhe2");
                //Console.WriteLine("id:{0},name:{1},phone:{2},classid:{3}", stu2.stuid, stu2.name, stu2.phone, stu2.classid);
                ////注意：AddObject方法中参数“entitySetName ”就是指对应实体名称，应该是：“T_StuInfo”，而不是“studentEntities.T_StuInfo”；
                #endregion

                #region 更新1：先取出来，再更新，然后保存，两次数据库连接，效率低

                //T_StuInfo stu1 = stuEntity.T_StuInfo.FirstOrDefault(c => c.name == "wangjinhe1");
                //stu1.name = "wangjinhe11"; //取出来后直接修改
                //stu1.phone = "121212121";
                //stu1.classid = 2;
                //stuEntity.SaveChanges();

                //T_StuInfo stu2 = stuEntity.T_StuInfo.FirstOrDefault(c => c.name == "wangjinhe11");
                //Console.WriteLine("id:{0},name:{1},phone:{2},classid:{3}", stu2.stuid, stu2.name, stu2.phone, stu2.classid);

                #endregion

                #region 直接更新 ：通过ObjectStateManage来控制添加、修改、删除队列以及实体的状态

                //T_StuInfo stu1 = new T_StuInfo();//假设这是DTO(数据传输对象)传递过来的对象
                //stu1.stuid = 2; //需要指明主键，否则报错
                //stu1.name = "西门春雪";
                //stu1.phone = "18790186666";
                //stu1.classid = 2;
                //stuEntity.T_StuInfo.Attach(stu1);//将对象附加到对象上下文中
                //stuEntity.ObjectStateManager.ChangeObjectState(stu1, EntityState.Modified);//修改状态
                //int result = stuEntity.SaveChanges();//保存到数据库，这样仅仅有一次连接数据库
                //Console.WriteLine(result);

                //stu1 = stuEntity.T_StuInfo.FirstOrDefault(c => c.stuid == 2);//取出来查看是否已经修改
                //Console.WriteLine("学号:{0}，姓名:{1},电话:{2},班级:{3}", stu1.stuid, stu1.name, stu1.phone, stu1.T_Class.name);

               

                #endregion

                #region 删除
                //T_StuInfo stu1 = stuEntity.T_StuInfo.FirstOrDefault(cc => cc.name == "王金河8");
                //stuEntity.DeleteObject(stu1);//删除对象
                //int result = stuEntity.SaveChanges();
                //Console.WriteLine(result);

                //T_StuInfo stu2 = stuEntity.T_StuInfo.FirstOrDefault(cc => cc.name == "王金河8");
                //if (stu2 == null)
                //{
                //    Console.WriteLine("您查找的数据已经删除");
                //}
              
                #endregion
            }

            #region 事务
            //studentEntities stuEntity2 = null; //数据库对象为空
            //System.Data.Common.DbTransaction tran = null; //事务对象为空
            //try
            //{
            //    stuEntity2 = new studentEntities();//新建数据库对象
            //    stuEntity2.Connection.Open();
            //    tran = stuEntity2.Connection.BeginTransaction();//开始事务
            //    T_StuInfo stu1 = stuEntity2.T_StuInfo.FirstOrDefault(cc => cc.name == "王金河7");
            //    stu1.phone = "13507611111";
            //    stu1.classid = 2;
            //    stuEntity2.SaveChanges();//保存更改
            //    tran.Commit();//提交事务
                   
            //}
            //catch(Exception ex)
            //{
            //    if (tran != null)
            //        tran.Rollback();//回滚事务
            //    throw ex;
            //}
            //finally
            //{
            //    if (stuEntity2 != null && stuEntity2.Connection.State != ConnectionState.Closed)
            //        stuEntity2.Connection.Close();
            //}           

            #endregion
            Console.WriteLine("OK");


            Console.Read();

           


        }
     
    }
}