Entity Framework，EF 手动DB FIRST，不使用设计器

环境:

VS2019

SQL SERVER 2012

一、在数据库（db1）创建表结构

“db1”是数据库名，“Table1”是表名。

USE [db1]
GO

/****** Object:  Table [dbo].[Table1]    Script Date: 2020/12/30 10:14:54 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Table1](
    [aa] [bigint] IDENTITY(1,1) NOT NULL,
    [bb] [nvarchar](50) NULL,
    [cc] [nvarchar](50) NULL,
 CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED 
(
    [aa] 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

二、在VS里新建一个WINFORM项目

基于.NET FRAMEWORK 4.5.2

1.使用nuget下载“EntityFramework”，此时最新版本是6.4.4。

下载成功后，可以观察到app.config已被自动修改，在原有基础上新增了“configSections”、“entityFramework”两个配置节。原始只有“startup”。

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
        <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
        <section name="entityFramework"
          type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
          requirePermission="false"/>
    </configSections>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2"/>
    </startup>

  <connectionStrings>
    <add name="Db1Context" connectionString="Data Source=localhost;Initial Catalog=db1;MultipleActiveResultSets=True;User ID=sa;Password=som;Pooling=true;" providerName="System.Data.SqlClient"/>
  </connectionStrings>
  
    <entityFramework>
        <providers>
            <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer"/>
        </providers>
    </entityFramework>
</configuration>

2.新建“Table1”实体类，并设置主键和自增长列，与表结构保持一致

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace WindowsFormsEFdbFirst.DbModel
{
    public class Table1
    {
        [Key] //主键 
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]  //设置自增
        public long aa { get; set; }

        public string bb { get; set; }

        public string cc { get; set; }

    }
}

3.新建“Db1DbContext”

using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;
using WindowsFormsEFdbFirst.DbModel;

namespace WindowsFormsEFdbFirst.DbContext2
{
    public class Db1DbContext : DbContext
    {
        public Db1DbContext()
            : base("name=Db1Context")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            //移除复数表名
            modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
            
            base.OnModelCreating(modelBuilder);
        }

        public virtual DbSet<Table1> Table1s { get; set; }
    }
}

4.界面上添加一个BUTTON，双击添加点击事件。

private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                using (Db1DbContext db1 = new Db1DbContext())
                {
                    Table1 t1 = new Table1();
                    t1.bb = "bb" + DateTime.Now.ToString();
                    t1.cc = "c" + DateTime.Now.ToString();

                    db1.Table1s.Add(t1);
                    db1.SaveChanges();
                }
                MessageBox.Show("完成");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

插入一条记录做演示。