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实体关系

28810 edited this page Jul 15, 2019 · 34 revisions

自定义导航关系

//导航属性,OneToMany
[Navigate("song_id")]
public virtual List<song_tag> Obj_song_tag { get; set; }

//导航属性,ManyToOne/OneToOne
[Navigate("song_id")]
public virtual Song Obj_song { get; set; }

//导航属性,ManyToMany
[Navigate(ManyToMany = typeof(tag_song))]
public virtual List<tag> tags { get; set; }
  • 可约定,可不约定;
  • 不约定的,需指定 Navigate 特性关联;
  • 无关联的,查询时可以指明 On 条件,LeftJoin(a => a.Parent.Id == a.ParentId);
  • 已关联的,直接使用导航对象就行,On 条件会自动附上;

约定配置

OneToOne 一对一

class User {
    public int Id { get; set; } //Id、UserId、User_id

    public UserExt UserExt { get; set; }
}

class UserExt {
    public int id { get; set; } //Id、UserId、User_id、UserExtId、UserExt_id

    public User User { get; set; }
}

《OneToOne 一对一,怎么添加数据?》

ManyToOne 多对一

class Group {
    public int Id { get; set; } //Id、GroupId、Group_id
}

class User {
    public int Id { get; set; } //Id、UserId、User_id


    public int AGroupId { get; set; }
    public Group AGroup { get; set; }

    public int BGroupId { get; set; }
    public Group BGroup { get; set; }
}

OneToMany 一对多

class Group {
    public int Id { get; set; } //Id、GroupId、Group_id

    public ICollection<User> AUsers { get; set; }
    public ICollection<User> BUsers { get; set; }
}

class User {
    public int Id { get; set; } //Id、UserId、User_id


    public int AGroupId { get; set; }
    public Group AGroup { get; set; }

    public int BGroupId { get; set; }
    public Group BGroup { get; set; }
}

《OneToMany 一对多,怎么添加数据?》

Parent 父子

class Group {
    public int Id { get; set; } //Id、GroupId、Group_id

    public int ParentId { get; set; } //ParentId、Parent_id
    public Group Parent { get; set; }

    public ICollection<Group> Childs { get; set; }
}

父子关系,与一对多其实差不多,添加数据参数上面的连接;

ManyToMany 多对多

class Song {
    [Column(IsIdentity = true)]
    public int Id { get; set; }
    public string Title { get; set; }

    public virtual ICollection<Tag> Tags { get; set; }
}
class Song_tag {
    public int Song_id { get; set; }
    public virtual Song Song { get; set; }

    public int Tag_id { get; set; }
    public virtual Tag Tag { get; set; }
}
class Tag {
    [Column(IsIdentity = true)]
    public int Id { get; set; }
    public string Name { get; set; }

    public int? Parent_id { get; set; }
    public virtual Tag Parent { get; set; }

    public virtual ICollection<Song> Songs { get; set; }
    public virtual ICollection<Tag> Tags { get; set; }
}

Song、Tag、Song_tag,这三个实体使用了 OneToMany、ManyToOne、Parent、ManyToMany 4种关系。

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