需要的LINQ相当于

Question

帮助中找到的LINQ等效于以下SQL查询：

select sum(weight) from (
select weight from pers p 
join list l on l.persindex= p.persindex 
group by p.persindex,weight) a 

Answer 1

VB.NET版本

Dim customerList = From p In pers 
        Group Join l In list On 
        p.persindex Equals l.persindex 
        Into joineddata = Group, 
         TotalOweight = Sum(p.weight) 
        Select p.persindex, TotalOweight 

---

尝试：Linquer SQL to LINQ convertion tool：

from p in pers 
joins l in list on l.persindex equals p.persindex 
group by new {p.persindex,l.weight } into grp 
select new { sum = grp.sum(x=>x.weight)} 

Answer 2

from p in context.pers 
join l in context.list on l.persindex equals p.persindex 
group by new 
{  p.persindex, 
     l.weight 
} into myGroup 
select new() 
{  Key = myGroup.Key, 
     GroupSum = myGroup.sum(x=>x.weight) 
} 

Answer 3

我想这就是你需要：

public int CalcWeight(IEnumerable<Person> pers, IEnumerable<Person> list) 
{ 
    return 
     pers 
     .Join(list, p=>p.PersIndex, l=>l.PersIndex, (p, l) => new {p.PersIndex, l.Weight}) 
     .GroupBy(a => new {a.PersIndex, a.Weight}) 
     .Sum(group=>group.Key.Weight); 
} 

数据类人是decalerd这样的：

public class Person 
{ 
    public int PersIndex; 
    public int Weight; 
}