Question

I have an SQL code like;

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

I would like to convert this to LINQ, but no luck. I am using LINQ to Object. Any help would be appreciated.
TIA

EDIT : Here is some sample data, and the expected result.

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 });

I have removed “where” from my first query as its not a problem at the moment.

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)