C# 插入、删除、更新（多对多关系）

在中描述了关于多对多数据关系的关系

现在如何在

CourseInstructo

上执行插入、删除和更新

对于一对一的关系，我这样做：

var  context= new Modle2();
var course= new Course() {title="math",...};
context.Course.addObject(course);
context.SaveChanges()

---

您可以在任意一端使用导航属性来操纵多对多关系。 比如说,

using (var context = new Model2())
{
    int courseID = 4022;
    var course = (from c in context.Courses
                 where c.CourseID == courseID
                 select c).First();

    int personID = 17;
    var instructor = (from p in context.Person
                  where p.PersonID == personID
                  select p).First();

    course.Person.Add(instructor);
    // alternatively, this will also do - instructor.Course.Add(course);
    context.SaveChanges();
}

using (var context = new Model2())
{
    int courseID = 4022;
    var course = (from c in context.Courses
                 where c.CourseID == courseID
                 select c).First();

    int personID = 17;
    var instructor = (from p in context.Person
                  where p.PersonID == personID
                  select p).First();

    course.Person.Remove(instructor);
    context.SaveChanges();
}

要删除，请使用类似的逻辑-例如

using (var context = new Model2())
{
    int courseID = 4022;
    var course = (from c in context.Courses
                 where c.CourseID == courseID
                 select c).First();

    int personID = 17;
    var instructor = (from p in context.Person
                  where p.PersonID == personID
                  select p).First();

    course.Person.Add(instructor);
    // alternatively, this will also do - instructor.Course.Add(course);
    context.SaveChanges();
}

using (var context = new Model2())
{
    int courseID = 4022;
    var course = (from c in context.Courses
                 where c.CourseID == courseID
                 select c).First();

    int personID = 17;
    var instructor = (from p in context.Person
                  where p.PersonID == personID
                  select p).First();

    course.Person.Remove(instructor);
    context.SaveChanges();
}

---

更新对多对多关系没有意义-它本质上是添加和删除组合。

@MaEb，您是否遇到编译时错误或运行时异常。或者只是代码运行时没有错误，但什么也没有发生。在这两种情况下，请尝试发布相关代码。