C# 错误：“StudentScore”是一个类型，在给定上下文中无效

加入两个集合，按科目计算每个学生的总分

public class Student
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

    public class StudentScore
    {
        public int StudentId { get; set; }
        public string Subject { get; set; }
        public int Points { get; set; }
    }
public class StudentScoress
    {

        public static void Main(string[] args)
        {
            var totalscore = from s in Student
                             join ss in StudentScore
                             on s.Id equals ss.StudentId
                             group ss by ss.Subject into sss
                             select new { sss.Name, sss.Subject, sss.Points };

            foreach (var ts in totalscore)
            {
                Console.WriteLine("{0}" + " " + "{1}" + " " + "{2}", ts.Name, ts.Subject, ts.Points);
            }
        }

        IEnumerable<Student> student = new List<Student>()
        {
            new Student() {Id=1,Name="Sam",Age=16},
            new Student() {Id=2,Name="Rick",Age=16},
            new Student() {Id=3,Name="Warner",Age=17},
        };

        IEnumerable<StudentScore> studentScores = new List<StudentScore>()
        {
            new StudentScore() { StudentId = 1, Subject = "Maths", Points = 54},
            new StudentScore() { StudentId = 1, Subject = "Maths", Points = 32},
            new StudentScore() { StudentId = 1, Subject = "English", Points = 55},      
            new StudentScore() { StudentId = 1, Subject = "English", Points = 54},
            new StudentScore() { StudentId = 1, Subject = "Biology", Points = 32},
            new StudentScore() { StudentId = 1, Subject = "Biology", Points = 27},          

            new StudentScore() { StudentId = 2, Subject = "Maths", Points = 44},
            new StudentScore() { StudentId = 2, Subject = "Maths", Points = 37},
            new StudentScore() { StudentId = 2, Subject = "English", Points = 59},  
            new StudentScore() { StudentId = 2, Subject = "English", Points = 64},
            new StudentScore() { StudentId = 2, Subject = "Biology", Points = 42},
            new StudentScore() { StudentId = 2, Subject = "Biology", Points = 67},          

            new StudentScore() { StudentId = 3, Subject = "Maths", Points = 53},
            new StudentScore() { StudentId = 3, Subject = "Maths", Points = 72},            
            new StudentScore() { StudentId = 3, Subject = "English", Points = 54},
            new StudentScore() { StudentId = 3, Subject = "English", Points = 59},
            new StudentScore() { StudentId = 3, Subject = "Biology", Points = 87},
            new StudentScore() { StudentId = 3, Subject = "Biology", Points = 34}
        };
    }

我在LINQ查询中发现一个错误，即“StudentScore”是一个类型，在给定上下文中无效

我错过了什么。有人帮我吗

您应该用学生列表替换学生模型。 您应该用studentScores列表替换studentScores模型。 您需要通过两个字段对新的{s.Name，ss.Subject}进行分组，以便能够获得选择结果。 使用聚合运算符（如Sum函数）来获取TotalScore等。 输出

---

它必须来自s in student加入ss in studentScores-您必须引用您的变量，而不是查询中的类。@germi Thank..它提供了一个清晰的说明。非常感谢@Phong想问一些问题以供我澄清。1.如果我将IEnumerables放在main方法之外，如何调用student和studentScores变量。2.为什么我要在“分组依据”中添加“姓名”字段，因为我想根据主题分组依据。3.如何在输出中显示输出而不重复名称，如名称：Sam，科目总分：{“数学”：86，“英语”：109，“生物学”：59}1。为什么要将其置于方法之外？您可以创建其他方法，如GetListOfStudents等。之后，您可以调用该方法。在第二个问题中，我们应该尽量保持问题的简单性，以便将来帮助读者。这样你就可以提出另一个问题了？与相应的结果。把问题链接发给我。我愿意帮助你。当然可以@phong。。我将在即将发布的帖子中遵循您的建议。

        var totalscore = from s in student
            join ss in studentScores on s.Id equals ss.StudentId
            group ss by new {s.Name, ss.Subject} into sss
            select new { sss.Key.Name, sss.Key.Subject, TotalScore = sss.Sum(p => p.Points)  };

        foreach (var ts in totalscore)
        {
            Console.WriteLine("{0}" + " " + "{1}" + " " + "{2}", ts.Name, ts.Subject, ts.TotalScore);
        }

Sam Maths 86
Sam English 109
Sam Biology 59
Rick Maths 81
Rick English 123
Rick Biology 109
Warner Maths 125
Warner English 113
Warner Biology 121