学步园

前面介绍了DataContext类，它可以用来映射和连接数据库，执行SQL命令，跟踪实体对象的状态。

下面介绍Table<TEntity>表示表格记录，它是一个泛型集合类，它的元素就是表格实体对象。它提供一组方法，对元素进行添加删除操作，并可以通过DataContext将这些操作保存到数据库。

表还是前面的那张表，在项目中添加了一个LINQ to SQL类。重点是InsertOnSubmit、DeleteOnSubmit等方法。

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

namespace LINQ_to_SQL_Table
{
    /// <summary>
    /// 操作单一表格的Table<TEntity>类
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            //1.a.Attach附加实体
            DataClasses1DataContext dc1 = new DataClasses1DataContext();
            tb_GuestInfo guset = new tb_GuestInfo() { Id=1, Name = "DebugLZQ", Age = 35, Tel = "138****8888" };

            dc1.tb_GuestInfo.Attach(guset);//这样的Attach仅仅附加实体，数据库没有更新
            dc1.SubmitChanges();
            //显示附加成功
            foreach (var g in dc1.tb_GuestInfo)
            {
                Console.WriteLine("{0} {1} {2} {3}", g.Id, g.Name, g.Age, g.Tel);
            }
            Console.WriteLine("---------");
            //显示数据库没有更新
            DataClasses1DataContext dc2 = new DataClasses1DataContext();
            foreach (var g in dc2.tb_GuestInfo)
            {
                Console.WriteLine("{0} {1} {2} {3}", g.Id, g.Name, g.Age, g.Tel);
            }
            Console.WriteLine("------------------------");
            Console.ReadKey();

            //2.InsertOnSubmit
            dc2.tb_GuestInfo.InsertOnSubmit(guset);
            dc2.SubmitChanges();

            foreach (var g in dc2.tb_GuestInfo)
            {
                Console.WriteLine("{0} {1} {2} {3}", g.Id, g.Name, g.Age, g.Tel);
            }
            Console.WriteLine("------------------------");
            Console.ReadKey();
            //2b.InsertAllOnSubmit 插入集合
            List<tb_GuestInfo> lst = new List<tb_GuestInfo>() 
            {
                new tb_GuestInfo(){ Name="AA", Age=25,Tel="133****3333"},
                new tb_GuestInfo(){ Name="BB", Age=25,Tel="135****5555"}
            };
            dc2.tb_GuestInfo.InsertAllOnSubmit(lst);
            dc2.SubmitChanges();

            foreach (var g in dc2.tb_GuestInfo)
            {
                Console.WriteLine("{0} {1} {2} {3}", g.Id, g.Name, g.Age, g.Tel);
            }
            Console.WriteLine("------------------------");
            Console.ReadKey();
            //
            //3.DeleteOnSubmit
            tb_GuestInfo entity = (from g in dc2.tb_GuestInfo
                                   where g.Name == "AA"
                                   select g).Single();
            dc2.tb_GuestInfo.DeleteOnSubmit(entity);//
            dc2.SubmitChanges();

            foreach (var g in dc2.tb_GuestInfo)
            {
                Console.WriteLine("{0} {1} {2} {3}", g.Id, g.Name, g.Age, g.Tel);
            }
            Console.WriteLine("------------------------");
            Console.ReadKey();
            //3b.DeleteAllOnSubmit
            IEnumerable<tb_GuestInfo> entitys = from g in dc2.tb_GuestInfo
                                                where g.Name == "AA" || g.Name == "BB"
                                                select g;
            dc2.tb_GuestInfo.DeleteAllOnSubmit(entitys);
            dc2.SubmitChanges();

            foreach (var g in dc2.tb_GuestInfo)
            {
                Console.WriteLine("{0} {1} {2} {3}", g.Id, g.Name, g.Age, g.Tel);
            }
            Console.WriteLine("------------------------");
            Console.ReadKey();           
            
        }
    }
}

程序运行结果如下：