本文主要講EF一對多關系和多對多關系的建立

一、模型設計器

1、一對多關系

右鍵設計器新增關聯

導航屬性和外鍵屬性可修改

2、多對多關系

右鍵設計器新增關聯

模型設計完畢之後,根據右鍵設計器根據模型生成數據庫,就能生成對應的表之間的一對多和多對多關聯

二、代碼層面

建表語句如下:

--建表腳本
create table Student
(
    Id int not null,
    Name varchar(30) not null,
    Age int not null
)
create table Teacher
(
    Id int not null,
    Name 
 
varchar(30) not null,
    Age int not null
)

create table StudentTeacher
(
    StudentId int not null,
    TeacherId int not null
)

create table InfoCard
(
    Id int not null,
    [Money] int not null,
    StudentId int not null
)

添加常規主鍵約束,代碼如下:

--單主鍵約束
alter table Student add constraint [PK_People
 
]
primary key clustered (Id Asc)

alter table InfoCard add constraint [PK_InfoCard]
primary key clustered (Id Asc)

alter table Teacher add constraint [PK_Teacher]
primary key clustered (Id Asc)

1、一對多(通過外鍵)

--但外鍵約束(一對多)
alter table InfoCard add constraint [FK_InfoCard_Student]
foreign key (StudentId) references
 
 Student (Id) on delete no action on update no action

2、多對多(中間表雙主鍵雙外鍵)

--雙主鍵約束(多對多)
alter table StudentTeacher add constraint [PK_StudentTeacher]
primary key clustered (StudentId,TeacherId Asc)

--雙外鍵約束(多對多)
alter table StudentTeacher
add constraint [FK_StudentTeacher_Student]
foreign key (StudentId) references Student (Id) on delete no action on update no action --級聯更新級聯刪除

alter table StudentTeacher add constraint [FK_StudentTeacher_Teacher]
foreign key (TeacherId) references Teacher (Id) on delete no action on update no action 

生成對應的一對多和多對多關聯的表之後,根據數據庫生成模型就能生成對應的模型

EF基礎知識小記五(一對多、多對多處理)