Multiple group by and Sum LINQ

Question

I have a products sales table that looks like this:

saleDate     prod        qty
10/22/09     soap        10
09/22/09     pills       05
09/25/09     soap        06
09/25/09     pills       15

I need to make the SUM of each MONTH so the final table would look like this:

saleDate     prod        qty
10/09        soap        10
09/09        soap        06
09/09        pills       20

Can I do this with LINQ?

Answer 1

Sure.

It'll look like this:

var GroupedSales = 
      from p in products 
      group p by p.saleDate.Month into g 
      select new { saleMonth = g.saleDate.Month, QtySold = g.Sum(p => p.qty) };

See: http://msdn.microsoft.com/en-us/vcsharp/aa336747.aspx#sumGrouped

Also, note that I was operating under the assumption that your dataset only had 2009 data. If you want to group by month/year, you can use saleDate.ToString("yyyyMM") instead of saleDate.Month.

Answer 2

var products = new[] {
    new {SaleDate = new DateTime(2009,10,22), Product = "Soap", Quantity = 10},
    new {SaleDate = new DateTime(2009,09,22), Product = "Pills", Quantity = 5},
    new {SaleDate = new DateTime(2009,09,25), Product = "Soap", Quantity = 6},
    new {SaleDate = new DateTime(2009,09,25), Product = "Pills", Quantity = 15}
};

var summary = from p in products
              let k = new
              {
                   //try this if you need a date field 
                   //   p.SaleDate.Date.AddDays(-1 *p.SaleDate.Day - 1)
                  Month = p.SaleDate.ToString("MM/yy"),
                  Product = p.Product
              }
              group p by k into t
              select new
              {
                  Month = t.Key.Month,
                  Product = t.Key.Product,
                  Qty = t.Sum(p => p.Quantity)
              };

foreach (var item in summary)
    Console.WriteLine(item);

//{ Month = 10/09, Product = Soap, Qty = 10 }
//{ Month = 09/09, Product = Pills, Qty = 20 }
//{ Month = 09/09, Product = Soap, Qty = 6 }

Answer 3

var q = from s in sales
       group s by new {saleDate = s.saleDate.ToString("MM/yy"), s.prod} into g
       select new { g.Key.saleDate, g.Key.prod, qty = g.Sum(s => s.qty) };

Answer 4

class Program
{
    static void Main(string[] args)
    {
        var sales = new List<Sale>();
        sales.Add(new Sale() { Product = "soap", saleDate = new DateTime(2009, 10, 22), Quantity = 10});
        sales.Add(new Sale() { Product = "soap", saleDate = new DateTime(2009, 9,22), Quantity = 6});
        sales.Add(new Sale() { Product = "pills", saleDate = new DateTime(2009,9,25), Quantity = 15});
        sales.Add(new Sale() { Product = "pills", saleDate = new DateTime(2009,9,25), Quantity = 5});

        var q = from s in sales
                group s by new { s.Product, s.saleDate.Month, s.saleDate.Year } into g
                select new {Month = String.Format("{0:MM/yy}", new DateTime(g.Key.Year, g.Key.Month, 1)), product = g.Key.Product, quantity = g.Sum(o=>o.Quantity)};


    }
}

class Sale
{
    public DateTime saleDate { get; set; }
    public int Quantity { get; set; }
    public string Product { get; set; }
}