Question

My database has a sales table with entries like so:

_____________________________________
| id |  title_id   |       qty      |
-------------------------------------
| 0  |  6          |        10      |
-------------------------------------
| 1  | 5           |        5       |
-------------------------------------
| 2  |  6          |        2       |
-------------------------------------

Title_id is Foreign key pointing to Titles table which is as follows:

_____________________________________
| id |  title_id   |       title    |
-------------------------------------
| 0  |  5          |       Soda     |
-------------------------------------
| 1  |  6          |      Coffee    |
-------------------------------------

I want to find top 5 sold products wich means i need to calculate the qty value for each product for all it’s entried in sales table then order the result by qty in descending order and limit the select to 5.

However I’m new to C# ASP.NET and somewhat new to SQL. I dont know how to do this with LINQ.
This is my code so far:

        var getIds = (from sale in db.sales
                      join tit in db.titles on sale.title_id equals tit.title_id
                      group sale by sale.qty into result
                      orderby result.Sum(i => i.qty) descending
                      select new Publication 
                      { 
                        PubID = sales.title_id, Title = tit.title
                      }
                      ).Take(5);

Answer 1

Assuming you have a navigation property Sale.Title, something like this should do:

var tops = 
  db.Sales
    .GroupBy( o => o.Title )
    .Select( o => new { Title = o.Key, Sum = o.Sum( x => x.Quantity ) } )
    .OrderByDescending( o => o.Sum )
    .Take( 5 )
    .ToList();

tops is then a list of an anonymous type with two properties: the Title object and the sum of the quantities.

---

You can then get the values like this:

foreach( var top in tops )
{
  int titleId = top.Title.title_id;
  string title = top.Title.title;
  int sumOfQuantities = top.Sum;
  ...

---

If you just want the top Title objects, can can select them like this:

List<Title> topTitles = tops.Select( o => o.Title ).ToList();