通过LINQ to SQL中

Question

我试图写LINQ查询组：

SQL：

select s.s_name, sum(sub.evaluation) as suma from submit_task sub 
join student s on s.id=sub.student_id 
join study_group g on g.id=s.study_group_id 
where g.g_name="abcd" 
group by s.s_name 
order by suma desc 

Answer 1

var groupName = "abcd"; 
var query = 
    from submitTask in db.submit_task 
    join student in db.student 
     on submitTask.student_id equals student.id 
    join studyGroup in db.study_group 
     on student.study_group_id equals studyGroup.id 
    where studyGroup.g_name == groupName 
    group submitTask by student.s_name into g 
    let suma = g.Sum(st => st.evaluation) 
    orderby suma descending 
    select new 
    { 
     s_name = g.Key, 
     suma = suma, 
    }; 

Answer 2

看看这篇文章。 http://www.codeproject.com/Articles/35667/How-to-Use-LINQ-GroupBy1

作者描述了接近你所要求的