Entity Framework表拆分為多個實體

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概念

表拆分：一個表拆分成多個實體，例如Photograph表，可以拆分為Photograph和PhotographFullImage兩張表。

1、Photograph實體結構：

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstTableSplit.Model
{
    /// <summary>
    /// 縮略圖類
    /// </summary>
    public class Photograph
    {
        /// <summary>
        /// 設置PhotoId是主鍵 自動增長
        /// </summary>
        [Key]
        [DatabaseGenerated(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity)]
        public int PhotoId { get; set; }

        public string Title { get; set; }

        /// <summary>
        /// 縮略圖
        /// </summary>
        public byte[] ThumbnailBite { get; set; }

        /// <summary>
        /// Photograph通過導航屬性引用PhotographFullImage
        /// </summary>
        [ForeignKey("PhotoId")]
        public virtual PhotographFullImage PhotographFullImage { get; set; }
    }
}

 2、PhotographFullImage實體結構：

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstTableSplit.Model
{
    public class PhotographFullImage
    {
        [Key]
        public int PhotoId { get; set; }

        /// <summary>
        /// 高分辨率
        /// </summary>
        public byte[] HighResolutionBits { get; set; }

        /// <summary>
        /// PhotographFullImage通過導航屬性引用Photograph
        /// </summary>
        [ForeignKey("PhotoId")]
        public virtual Photograph Photograph { get; set; }
    }
}

 3、創建數據上下文對象子類：

using CodeFirstTableSplit.Model;
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstTableSplit.DatabaseContext
{
    public class EFDbContext :DbContext
    {
        public EFDbContext()
            : base("name=Default")
        { }

        public DbSet<Photograph> Photographs { get; set; }

        public DbSet<PhotographFullImage> PhotographFullImages { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            // 設置主體
            modelBuilder.Entity<Photograph>().HasRequired(p => p.PhotographFullImage).WithRequiredPrincipal(t => t.Photograph);

            // 生成同一張表:設置兩個實體有相同的表名
            modelBuilder.Entity<Photograph>().ToTable("Photograph");
            modelBuilder.Entity<PhotographFullImage>().ToTable("Photograph");
            base.OnModelCreating(modelBuilder);
        }


    }
}

 4、使用數據遷移生成數據庫結構，查看生成後的結構：

5、寫入數據

using CodeFirstTableSplit.DatabaseContext;
using CodeFirstTableSplit.Model;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstTableSplit
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var context = new EFDbContext())
            {
                // 寫入數據
                byte[] thumbBits = new byte[100];
                byte[] fullBits = new byte[2000];
                var photo = new Photograph() { Title = "李四", ThumbnailBite = thumbBits };
                var fullImage = new PhotographFullImage() { HighResolutionBits = fullBits };

                photo.PhotographFullImage = fullImage;
                context.Photographs.Add(photo);
                // 保存
                context.SaveChanges();
            }
            Console.WriteLine("創建成功");
            Console.ReadKey();
        }
    }
}

 6、查詢數據

到此這篇關於Entity Framework表拆分為多個實體的文章就介紹到這瞭。希望對大傢的學習有所幫助，也希望大傢多多支持WalkonNet。

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