LINQ RowNumber，Aggregate（Sum）和GroupBy

Question

我有一个像<; p>这样的SQL代码

Select GroupName, sum(LineAmount) as Total, WeekNumber,
    ROW_NUMBER() over (partition by WeekNumber order by sum(LineAmount) desc) as RowNum
from
    Invoices
where
    month(InvoiceDate)=month(getdate())
group by
    GroupName,WeekNumber

我想将此转换为LINQ，但没有运气。我正在使用LINQ to Object。任何帮助，将不胜感激。 TIA

编辑：这是一些示例数据和预期结果。

public class Invoice
{
    public string GroupName { get; set; }
    public int LineAmount { get; set; }
    public int WeekNum { get; set; }
}

   List<Invoice> theData = new List<Invoice>();
    theData.Add(new Invoice { GroupName = "A", LineAmount = 1, WeekNum = 1});
    theData.Add(new Invoice { GroupName = "A", LineAmount = 2, WeekNum = 1 });
    theData.Add(new Invoice { GroupName = "A", LineAmount = 3, WeekNum = 1 });
    theData.Add(new Invoice { GroupName = "A", LineAmount = 2, WeekNum = 2 });
    theData.Add(new Invoice { GroupName = "A", LineAmount = 3, WeekNum = 2 });
    theData.Add(new Invoice { GroupName = "A", LineAmount = 4, WeekNum = 2 });
    theData.Add(new Invoice { GroupName = "B", LineAmount = 4, WeekNum = 1 });
    theData.Add(new Invoice { GroupName = "B", LineAmount = 3, WeekNum = 1 });
    theData.Add(new Invoice { GroupName = "B", LineAmount = 7, WeekNum = 2 });
    theData.Add(new Invoice { GroupName = "B", LineAmount = 6, WeekNum = 2 });
    theData.Add(new Invoice { GroupName = "B", LineAmount = 5, WeekNum = 2 });

我已从第一个查询中删除了“where”，因为此时它不是问题。

Answer 1

theData
.GroupBy(g => new {g.GroupName, g.WeekNum}, (key, gg) => new {key.GroupName, key.WeekNum, Total = gg.Sum(g => g.LineAmount)})
.GroupBy(g => g.WeekNum, (weekNum, gg) => gg.OrderByDescending(g => g.Total).Select((g,i) => new {g.GroupName, g.Total, g.WeekNum, RowNum = i}))
.SelectMany(g => g)

Answer 2

您尚未指定所需的语言。以下是C＃中的代码

int index = 0;
var filteredInvoices = (from i in invoices
where i.InvoiceDate.Month == DateTime.Now().Month
group i by new { i.GroupName, i.WeekNumber }
into ig
select new {i.GroupName, Total = ig.Sum(i => i.LineAmount), i.WeekNumber, RowNum = ++index}).OrderByDescending(n => n.Total);

filteredInvoices应该具有您想要的结果。另外我假设i.InvoiceDate的类型是DateTime。

Answer 3

Serg Rogovtsev回答给了我预期的结果。以下代码就是我所做的。不知道哪个表现更好，但结果相同。

(theData.GroupBy(f => new { f.GroupName, f.WeekNum})
                .Select(r => new {r.Key.WeekNum, r.Key.GroupName, Total = r.Sum(f => f.LineAmount)}))
                .GroupBy(r => new {r.WeekNum}).SelectMany(
                    g =>
                    g.OrderByDescending(f => f.Total).Select(
                        (f, index) => new { f.GroupName, f.Total, f.WeekNum, Ix = index + 1 }))