C# 如何在LINQ中执行以下查询？

我想使用LINQ执行以下查询：

• 所有单位的计数
• 所有单元得分和总分之和
• 平均：分数分数分数%Totalmarks*100 4）排名
• 基于分数排名（如果user1只完成了单元id为100和101的2个单元，则应与其他用户进行比较）

DB:

代码：

---

您的自适应函数以及我引入的用于存储结果的额外类：

public class UserRankObject
{
    public int Rank { get; set; }
    public int UserId { get; set; }
    public float AverageScore { get; set; }
}
public UserRankObject GetUserRankObject(int? Student_ID, int? CourseID, int? SemID, int? SubjectID)
{
    // TODO: add null checks for arguments, or make them non-nullable.
    var scoreCard =
        dbcontext.Stu_Result
            .Where(u => u.CourseID == CourseID
                     && u.SemID == SemID
                     && u.SubjectID == SubjectID);

    return scoreCard.GroupBy(u => u.UserID)
       .OrderByDescending(g => g.Average(u => u.ScoredMarks / u.TotalMarks * 100))
       .Select((g, i) => new UserRankObject
       {
           UserId = g.Key,
           Rank = i + 1,
           AverageScore = g.Average(u => u.ScoredMarks / u.TotalMarks * 100)
       })
       .Single(u => u.UserId == Student_ID);
}

用法：

var ranked = new List<UserRankObject>()
{
    GetUserRankObject(1022, 109, 3000, 2006),
    GetUserRankObject(1021, 109, 3000, 2006)
};
Console.WriteLine("Ranked: \n" + string.Join("\n", ranked.Select(r => $"{r.Rank}. {r.UserId} ({r.AverageScore})")));
/*
Ranked:
1. 1022 (77.5)
2. 1021 (51.66667)
*/

var排名=新列表（）
{
GetUserRankObject（102210930002006），
GetUserRankObject（102110930002006）
};
Console.WriteLine（“排名：\n”+string.Join（“\n”，排名.Select（r=>$”{r.Rank}.{r.UserId}（{r.AverageScore}）”））；
/*
排列：
1.1022 (77.5)
2.1021 (51.66667)
*/

user id with 1021已完成3个单元90+40+35与其他用户相比，此分数不单unit@Arfat，请参阅编辑。这就是你想要的吗？我正在传递userid courseid semid subject，我需要一个Linq查询，在那里我可以得到学生的平均分数和排名。排名：例如，如果用户使用不同的id完成了2个单元，那么该id单元的分数仅与其他用户进行比较。请查看编辑的数据库userid 1022已完成2个单元（id:100和101）userid 1021已完成3个单元（id:100101102），如果我通过userid（1022）courseid（109）semid（3000）subjectid（2006）然后结果应为平均值，即得分标记/总分*100，即77.5，用户1022的排名为1，用户1021的排名为b2@Arfat，请参阅编辑。这是你想要的吗？您也不需要

semid

、

subjectid

和

courseid

甚至

userid

，因为它们不参与计算。您是否尝试过调用

Sum（）

或

Count（）

方法？

public class UserRankObject
{
    public int Rank { get; set; }
    public int UserId { get; set; }
    public float AverageScore { get; set; }
}
public UserRankObject GetUserRankObject(int? Student_ID, int? CourseID, int? SemID, int? SubjectID)
{
    // TODO: add null checks for arguments, or make them non-nullable.
    var scoreCard =
        dbcontext.Stu_Result
            .Where(u => u.CourseID == CourseID
                     && u.SemID == SemID
                     && u.SubjectID == SubjectID);

    return scoreCard.GroupBy(u => u.UserID)
       .OrderByDescending(g => g.Average(u => u.ScoredMarks / u.TotalMarks * 100))
       .Select((g, i) => new UserRankObject
       {
           UserId = g.Key,
           Rank = i + 1,
           AverageScore = g.Average(u => u.ScoredMarks / u.TotalMarks * 100)
       })
       .Single(u => u.UserId == Student_ID);
}

var ranked = new List<UserRankObject>()
{
    GetUserRankObject(1022, 109, 3000, 2006),
    GetUserRankObject(1021, 109, 3000, 2006)
};
Console.WriteLine("Ranked: \n" + string.Join("\n", ranked.Select(r => $"{r.Rank}. {r.UserId} ({r.AverageScore})")));
/*
Ranked:
1. 1022 (77.5)
2. 1021 (51.66667)
*/

public GetCalculatePerform(int? Student_ID, int? CourseID, int? SemID, int? SubjectID)
{           
    var scoreCard = dbcontext.Stu_Result
    .Where(u => u.CourseID == CourseID && u.SemID == SemID && u.SubjectID == SubjectID )
    .ToList()
    .GroupBy(u => u.UserID)
    .OrderByDescending(grp => grp.Average(u => u.ScoredMarks))
    .Select((grp, i) => new
    {
        UserId = grp.Key,
        Rank = i + 1,
        AverageScore = grp.Average(u => u.ScoredMarks)
    }).ToList().Single(u => u.UserId == Student_ID);
}

 public class GetCalculatePerform
    {

 abcEntities dbcontext = new abcEntities();

        public UserRankObject tempobj { get; set; }


        //********************************************************Performance & Rank Calculation********************************************


      public  GetCalculatePerform(int? Student_ID, int? CourseID, int? SemID, int? SubjectID)
        {


                var scoreCard = dbcontext.Stu_Result
                .Where(u => u.CourseID == CourseID && u.SemID == SemID && u.SubjectID == SubjectID)
                .ToList()
                .GroupBy(u => u.UserID)
                .OrderByDescending(grp => grp.Average(u => u.ScoredMarks))
                .Select((grp, i) => new UserRankObject
                {
                    UserId = grp.Key,
                    Rank = i + 1,
                    AverageScore = grp.Average(u => u.ScoredMarks)
                }).ToList().Single(u => u.UserId == Student_ID);
                // .FirstOrDefault(u=>u.UserId == Student_ID);


                this.tempobj = scoreCard;


      }

    }