EF-CodeFirst 增删改查（zhuan）

Posted 2020-10-10 Zoe

EF Code First增删改查

1、创建项目及下载Entity Framework

　　创建项目如下：

　　项目中安装Entity Framework：

2、数据库连接、实体类及映射文件配置

　　数据库连接配置文件：App.config

<?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=4.4.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="Data Source=(local); User ID=sa; Password=1; MultipleActiveResultSets=True" />
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>
</configuration>

　　实体类文件：Province.cs

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

namespace Northwind.App.Entities
{
    public class Province
    {
        /// <summary>
        /// 省份ID
        /// </summary>
        public Guid ProvinceID { get; set; }

        /// <summary>
        /// 省份编号
        /// </summary>
        public string ProvinceNo { get; set; }

        /// <summary>
        /// 省份名称
        /// </summary>
        public string ProvinceName { get; set; }
    }
}

　　实体类映射文件：ProvinceMap.cs

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

using System.Data.Entity.ModelConfiguration;
using System.ComponentModel.DataAnnotations.Schema;

using Northwind.App.Entities;

namespace Northwind.App.Mapping
{
    public class ProvinceMap : EntityTypeConfiguration<Province>
    {
        public ProvinceMap()
        {
            // Primary Key
            this.HasKey(t => t.ProvinceID);

            // Properties
            this.Property(t => t.ProvinceNo).HasMaxLength(10);

            this.Property(t => t.ProvinceName).HasMaxLength(50);

            // Table & Column Mappings
            this.ToTable("Province");
            this.Property(t => t.ProvinceID).HasColumnName("ProvinceID").HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
            this.Property(t => t.ProvinceNo).HasColumnName("ProvinceNo");
            this.Property(t => t.ProvinceName).HasColumnName("ProvinceName");
        }
    }
}

　　数据库操作上下文：NorthwindContext.cs

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

using System.Data.Entity;

using Northwind.App.Entities;
using Northwind.App.Mapping;

namespace Northwind.App
{
    public class NorthwindContext : DbContext
    {
        public DbSet<Province> Provinces { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new ProvinceMap());
        }
    }
}

 　　3、新增

　　代码：

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

using Northwind.App.Entities;

namespace Northwind.App
{
    class Program
    {
        static void Main(string[] args)
        {
            Province province = new Province { ProvinceID = Guid.NewGuid(), ProvinceNo = "100000", ProvinceName = "北京" };
            using (NorthwindContext db = new NorthwindContext())
            {
                db.Provinces.Add(province);
                db.SaveChanges();
            }
        }
    }
}

　　执行的Sql语句：

exec sp_executesql N\'insert [dbo].[Province]([ProvinceID], [ProvinceNo], [ProvinceName])
values (@0, @1, @2)
\',N\'@0 uniqueidentifier,@1 nvarchar(10),@2 nvarchar(50)\',@0=\'F0427980-6CB6-4D5B-91F5-ADE3E676DEA1\',@1=N\'100000\',@2=N\'北京\'

 　　4、修改

　　代码：

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

using System.Data;

using Northwind.App.Entities;

namespace Northwind.App
{
    class Program
    {
        static void Main(string[] args)
        {
            Province province = new Province { ProvinceID = new Guid("F0427980-6CB6-4D5B-91F5-ADE3E676DEA1"), ProvinceNo = "100000", ProvinceName = "上海" };
            using (NorthwindContext db = new NorthwindContext())
            {
                db.Entry(province).State = EntityState.Modified;
                db.SaveChanges();
            }
        }
    }
}

　　执行的Sql语句：

exec sp_executesql N\'update [dbo].[Province]
set [ProvinceNo] = @0, [ProvinceName] = @1
where ([ProvinceID] = @2)
\',N\'@0 nvarchar(10),@1 nvarchar(50),@2 uniqueidentifier\',@0=N\'100000\',@1=N\'上海\',@2=\'F0427980-6CB6-4D5B-91F5-ADE3E676DEA1\'

 　　5、删除

　　代码1：

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

using System.Data;

using Northwind.App.Entities;

namespace Northwind.App
{
    class Program
    {
        static void Main(string[] args)
        {

            Province province = new Province { ProvinceID = new Guid("F0427980-6CB6-4D5B-91F5-ADE3E676DEA1") };
            using (NorthwindContext db = new NorthwindContext())
            {
                db.Provinces.Attach(province);
                db.Provinces.Remove(province);
                db.SaveChanges();
            }
        }
    }
}

　　代码2：

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

using System.Data;

using Northwind.App.Entities;

namespace Northwind.App
{
    class Program
    {
        static void Main(string[] args)
        {

            Province province = new Province { ProvinceID = new Guid("F0427980-6CB6-4D5B-91F5-ADE3E676DEA1") };
            using (NorthwindContext db = new NorthwindContext())
            {
                db.Entry(province).State = EntityState.Deleted;
                db.SaveChanges();
            }
        }
    }
}

　　执行的Sql语句：

exec sp_executesql N\'delete [dbo].[Province]
where ([ProvinceID] = @0)\',N\'@0 uniqueidentifier\',@0=\'F0427980-6CB6-4D5B-91F5-ADE3E676DEA1\'

 　　6、查询

　　代码：

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

namespace Northwind.App
{
    class Program
    {
        static void Main(string[] args)
        {
            using (NorthwindContext db = new NorthwindContext())
            {
                var expr = from p in db.Provinces
                           select p;

                foreach (var item in expr)
                {
                    Console.WriteLine("{0}-{1}-{2}", item.ProvinceID, item.ProvinceNo, item.ProvinceName);
                }
            }
        }
    }
}

　　执行的Sql语句：

SELECT 
[Extent1].[ProvinceID] AS [ProvinceID], 
[Extent1].[ProvinceNo] AS [ProvinceNo], 
[Extent1].[ProvinceName] AS [ProvinceName]
FROM [dbo].[Province] AS [Extent1]

　　以上全部代码为Entity Framework Code First的基本增删改查的操作，仅为第一步使用Entity Framework Code First操作Sql Server数据库。

分类: Entity Framework