02—EF初次体验

新建个表，我用的是sql server2014，我会把文件发上来，如果是低版本的，可以执行语句，数据库就自己创建吧。

USE [testdb]
GO

CREATE TABLE [dbo].[Product](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [ProductId] [nvarchar](50) NULL,
    [ProductCode] [nvarchar](50) NULL,
    [ProductName] [nvarchar](255) NULL,
    [MarkPrice] [decimal](18, 2) NULL,
    [TruePrice] [decimal](18, 2) NULL,
    [Discount] [nvarchar](10) NULL,
    [IsWebPub] [int] NULL,
    [CityId] [int] NULL,
    [CityName] [nvarchar](50) NULL,
    [Sort] [decimal](18, 0) NULL,
    [Createtime] [datetime] NULL,
    [IsDelete] [int] NULL,
 CONSTRAINT [PK_Product] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

我创建了一个控制台应用程序，就不截图了

创建一个数据实体模型，也就是EDMX

数据库连接字符串，在App.config中

</connectionStrings>

来吧，写个增删改查：

            //增加
            Product p1 = new Product()
            {
                CityId = 1,
                CityName = "北京",
                Createtime = DateTime.Now,
                Discount = "22",
                IsWebPub = 1,
                ProductId = "3",
                ProductCode = "0001",
                MarkPrice = 50,
                ProductName = "苹果",
                Sort = 1,
                TruePrice = 20
            };
            Product p2 = new Product()
            {
                CityId = 2,
                CityName = "上海",
                Createtime = DateTime.Now,
                Discount = "22",
                IsWebPub = 1,
                ProductId = "2",
                ProductCode = "0002",
                MarkPrice = 6,
                ProductName = "大Y梨",
                Sort = 1,
                TruePrice = 5
            };
            using (mytestdbEntities dbefadd = new mytestdbEntities())
            {
                dbefadd.Product.Add(p1);
                dbefadd.Product.Add(p2);
                int retnum = dbefadd.SaveChanges();
                Console.WriteLine("add_{0}_ok", retnum);
            }
           //add_2_ok

           //删除
            using (mytestdbEntities dbefdel = new mytestdbEntities())
            {
                //删除一条
                // dbefdel.Product.Remove(p1);
                // dbefdel.SaveChanges();
                var entitys = dbefdel.Product.Where(p => p.ProductId == "1");
                //删除多条
                dbefdel.Product.RemoveRange(entitys);
                int retnum = dbefdel.SaveChanges();
                Console.WriteLine("del_{0}_ok", retnum);
            }

            //修改
            using (mytestdbEntities dbefedit = new mytestdbEntities())
            {
                var p = dbefedit.Product.FirstOrDefault();
                p.ProductName = "就把你名字改了";
                int retnum = dbefedit.SaveChanges();
                Console.WriteLine("edit_{0}_ok", retnum);
            }

            //查询
            using (mytestdbEntities dbefsel = new mytestdbEntities())
            {
                //查询一条
                var p = dbefsel.Product.FirstOrDefault();
                Console.WriteLine("查询一条：{0}|{1}|{2}|{3}", p.ProductId, p.ProductName, p.ProductCode, p.TruePrice);
                //查询一个集合
                var list = dbefsel.Product.Where(pp => pp.ProductId == "2");
                foreach (var item in list)
                {
                    Console.WriteLine("查询多条：{0}|{1}|{2}|{3}", item.ProductId, item.ProductName, item.ProductCode, item.TruePrice);
                }
                Console.WriteLine("sel_ok");
            }
            Console.ReadLine();

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