Question

我不知道这里发生了什么，想知道是否有人可以解决我的问题。我正在尝试用我的数据库中的＆lt; = 2到“Jerry”的teacher_Id替换所有First_names。

foreach标有错误并说：

无法将'string'类型转换为'Project.TeacherDetail'

private void button3_Click(object sender, EventArgs e)
    {
        ProjectDBDataContext Context = new ProjectDBDataContext();
        var r =
                from b in Context.TeacherDetails
                where b.TeacherId <= 2
                select b.First_Name ;

           foreach (TeacherDetail b in r)            
              b.First_Name = "Jerry";

           Context.SubmitChanges();


    }

任何帮助都会受到很多赞赏

Answer 1

假设;

public class TeacherDetails 
{
    public string First_Name { get; set; }
    //....
}

你需要像这样实现它;

private void button3_Click(object sender, EventArgs e)
{
    ProjectDBDataContext Context = new ProjectDBDataContext();
    var r =
            from b in Context.TeacherDetails
            where b.TeacherId <= 2
            select b; //Remove .First_Name here

    foreach (TeacherDetail b in r)            
        b.First_Name = "Jerry";

    Context.SubmitChanges();
}

您选择的是string select b.First_Name，而您会在TeacherDetail中将其作为foreach进行循环。

在尝试更改数据库时，Foreach会加下划线

1 个答案: