通过Lambda表达式使用两个以上的列进行分组 [英] Group By using more than two columns by Lambda expression
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问题描述
我必须在lambda表达式中转换给定的linq查询.即
I have to convert my given linq query in lambda expression. i.e.
var scholars = (from scholar in db.Scholars
join suspension in db.Suspensions
on scholar.ID equals suspension.ScholarID
where suspension.StartDate >= startDate &&
suspension.EndDate <= endDate
group scholar by new { scholar.ID, scholar.FirstName, scholar.LastName }
into g
select new
{
FullName = g.Key.FirstName +" " + g.Key.LastName,
TotalSuspensionSum = g.Sum(x => x.Suspensions.Sum(y => y.SuspensionDays))
})
.ToList()
.OrderBy(x=> x.FullName);
推荐答案
这是您的lambda:
this is your lambda:
var scholars = db.Scholars.Join(db.Suspensions,
scholar => scholar.ID,
suspension => suspension.ScholarID,
(scholar, suspension) => new {scholar, suspension})
.Where(u => u.suspension.StartDate >= startDate &&
u.suspension.EndDate <= endDate)
.GroupBy(u => new { u.scholar.ID, u.scholar.FirstName, u.scholar.LastName })
.Select(u => new
{
FullName = u.Key.FirstName + " " + u.Key.LastName,
TotalSuspensionSum = u.Sum(x =>
x.scholar.Suspensions.Sum(y => y.SuspensionDays)
)
})
.OrderBy(x => x.FullName)
.ToList();
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