Entity Framework表拆分為多個實體
更新時間:2022年03月05日 09:44:04 作者:.NET開發(fā)菜鳥
這篇文章介紹了Entity Framework表拆分為多個實體的方法,文中通過示例代碼介紹的非常詳細。對大家的學習或工作具有一定的參考借鑒價值,需要的朋友可以參考下
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(chuàng)建數(shù)據(jù)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(shù)據(jù)遷移生成數(shù)據(jù)庫結構,查看生成后的結構:

5、寫入數(shù)據(jù)
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(shù)據(jù)
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(chuàng)建成功");
Console.ReadKey();
}
}
}6、查詢數(shù)據(jù)

到此這篇關于Entity Framework表拆分為多個實體的文章就介紹到這了。希望對大家的學習有所幫助,也希望大家多多支持腳本之家。
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