Question

我在数据库中有一个enity。我想创建现有实体的3个副本，仅在创建日期属性中更改。怎么做到这一点？

我用AsNoTracking加载了enity。并尝试在for循环中创建。但我只得到一个项目添加到db。

using(var database = new MyDbContext()) {
    MyModel myModel = database.Where(m => m.SomeProperty == someValue).AsNoTracking();

    for(int i=0;i<5;i++)
    {
        myModel.SomeOtherProperty = someOtherValue; //user changed a value  
        database.MyModels.Add(myModel); 
    }

    database.SaveChanges();
}

由于

Answer 1

好的，这就是它的完成方式。为表创建DDL：

    USE [Breaz] --Your database name here
GO

/****** Object:  Table [dbo].[CopyCloneTable]    Script Date: 12/29/2016 11:15:23 AM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[CopyCloneTable](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [PropertyToCopy] [varchar](10) NULL,
    [SomeOtherProperty] [varchar](10) NULL,
 CONSTRAINT [PK_CopyCloneTable] 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

SET ANSI_PADDING OFF
GO

添加一行：

/****** Script for SelectTopNRows command from SSMS  ******/
--USE  your db name instead of Breaz here
INSERT INTO  [Breaz].[dbo].[CopyCloneTable] ([PropertyToCopy], [SomeOtherProperty])
    VALUES ('copyme', -1)

右键单击您的项目并添加ADO.NET实体数据模型，将其命名为MyDb，并使用名为MyDbContext的连接添加您的表

以下是您的观点：

    public ActionResult Index9()  //this Method name can change
    {
        using (var database = new MyDbContext())
        {
            CopyCloneTable myModel = database.CopyCloneTables.Where(m => m.SomeOtherProperty
                == "-1").FirstOrDefault();

            for (int i = 0; i < 3; i++)
            {
                database.CopyCloneTables.Add(new CopyCloneTable
                {
                    PropertyToCopy = myModel.PropertyToCopy,
                    SomeOtherProperty = i.ToString()
                });
            }

            database.SaveChanges();
        }

        return View();
    }

C＃Entityframework如何复制/克隆实体

1 个答案: