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      using (var db = new NorthwindEntities()) {
        var query = from p in db.Products
              group p.ProductName by p.ProductName.Substring(0, 1) into g
              orderby g.Key
              select g;

        foreach (var group in query) {
          Console.WriteLine(group.Key);
          foreach (var name in group)
            Console.WriteLine("- " + name);
        }
      }                    

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A
- Aniseed Syrup
- Alice Mutton
B
- Boston Crab Meat
C
- Chai
- Chang
- Chef Anton's Cajun Seasoning
- Chef Anton's Gumbo Mix
- Carnarvon Tigers
- Côte de Blaye
- Chartreuse verte
- Chocolade
- Camembert Pierrot
[...]