Entity Framework 学习初级篇6EntityClient

1,

System.Data.EntityClient 命名空间是 实体框架的 .NET Framework 数据提供程序。EntityClient 提供程序使用存储特定的 ADO.NET 数据提供程序类和映射元数据与实体数据模型进行交互。EntityClient 首先将对概念性实体执行的操作转换为对物理数据源执行的操作。然后再将物理数据源返回的结果集转换为概念性实体。

代码如下：

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)
        {
            #region EntityConnection连接对象            
         
            //string con = "name = studentEntities"; //连接字符串
            ////连接字符串也可以这样写
            ////string con = System.Configuration.ConfigurationManager.ConnectionStrings["studentEntities"].ConnectionString;
            //using (EntityConnection econn = new EntityConnection(con))//构造连接对象
            //{                
            //    string esql = "select value c from studentEntities.T_StuInfo as c where c.stuid < 5";
            //    econn.Open();//建立与数据源的连接
            //    EntityCommand ecmd = new EntityCommand(esql, econn);//构造命令对象
            //    EntityDataReader ereader = ecmd.ExecuteReader(CommandBehavior.SequentialAccess);
            //    while (ereader.Read()) //如果有数据，该函数会读取一条数据
            //    {
            //        Console.WriteLine(ereader["name"]);
            //    }
            //    Console.WriteLine(ecmd.ToTraceString());

            //}
            #endregion

            #region EntityCommand命令对象
            //string con = "name=studentEntities";
            //using (EntityConnection econn = new EntityConnection(con))
            //{
            //    string esql = "select value c from studentEntities.T_StuInfo as c where c.stuid=4";//e sql语句
            //    econn.Open();//打开连接对象
            //    EntityCommand ecmd = econn.CreateCommand();//使用对象创建一个命令
            //    ecmd.CommandText = esql;  //命令语句
            //    EntityDataReader ereader = ecmd.ExecuteReader(CommandBehavior.SequentialAccess);
            //    if (ereader.Read())
            //    {
            //        Console.WriteLine(ereader["name"]);
            //    }
            //    Console.WriteLine(ecmd.ToTraceString());
            //}         

            #endregion

            #region EntityConnectionStringBuilder 创建和连接字符串
            //EntityConnectionStringBuilder esb = new EntityConnectionStringBuilder();
            //esb.Provider = "System.Data.SqlClient";//数据提供程序名字
            //esb.Metadata =@"res://*/Model2.csdl|res://*/Model2.ssdl|res://*/Model2.msl";  //连接字符串的元数据位置
            //esb.ProviderConnectionString = @"Data Source=DP-201208111000;Initial Catalog=student;Integrated Security=True;MultipleActiveResultSets=True;";
            //EntityConnection conn= new EntityConnection(esb.ConnectionString);//创建连接对象
            //conn.Open();           

            #endregion
        
            #region EntityParameter 
           
            //string con = "name = studentEntities ";
            //using (EntityConnection econn = new EntityConnection(con))
            //{
            //    string esql = "select value c from studentEntities.T_StuInfo as c order by c.stuid skip @start limit @end";

            //    econn.Open();
            //    EntityCommand ecmd = new EntityCommand(esql, econn);

            //    EntityParameter p1 = new EntityParameter("start", DbType.Int32);//构造参数
            //    p1.Value = 1;   //为参数赋值
            //    EntityParameter p2 = new EntityParameter("end", DbType.Int32);
            //    p2.Value = 4;
            //    ecmd.Parameters.Add(p1);//将参数增加到命令对象中
            //    ecmd.Parameters.Add(p2);
                
            //    //还可以使用下面的命令增加参数
            //    //ecmd.Parameters.AddWithValue("start", 0);
            //    //ecmd.Parameters.AddWithValue("end", 4);
            //    EntityDataReader ereader = ecmd.ExecuteReader(CommandBehavior.SequentialAccess);
            //    while (ereader.Read())
            //    {
            //        Console.WriteLine(ereader["name"]);
            //    }
            //    Console.WriteLine(ecmd.ToTraceString());//命令转化后使用了row_number()排序

            //}

            #endregion

            #region  EntityDataReader

            //string con = "name=studentEntities";
            //using (EntityConnection econn = new EntityConnection(con))
            //{
            //    string esql = "select value c from studentEntities.T_StuInfo as c order by c.stuid limit 10";
            //    econn.Open();
            //    EntityCommand ecmd = new EntityCommand(esql, econn);
            //    EntityDataReader ereader = ecmd.ExecuteReader(CommandBehavior.SequentialAccess);
            //    while (ereader.Read())
            //    {
            //        Console.WriteLine("{0},{1},{2},{3}", ereader[0], ereader[1], ereader[2], ereader[3]);
            //    }
            //    Console.WriteLine(ecmd.ToTraceString());
            //    //注意：SequentialAccess 提供一种方法，以便 DataReader 处理包含带有大二进制值的列的行。
            //    //使用SequentialAccess则需按顺序访问列，否则将抛异常

            //}

           

            #endregion


            Console.WriteLine("OK");


            Console.Read();

           


        }
     
    }
}

注：本程序使用的ef源是:link to ef