C# - LINQ Query Results in Duplicate Entries When Grouping by Multiple Fields
I've been banging my head against this for hours... I've been banging my head against this for hours... I'm currently facing an issue where my LINQ query is returning duplicate entries when I attempt to group by multiple fields. I'm using Entity Framework Core 5.0 and have a model structure like this: ```csharp public class Order { public int Id { get; set; } public string CustomerName { get; set; } public DateTime OrderDate { get; set; } public decimal TotalAmount { get; set; } } ``` I want to group the orders by `CustomerName` and `OrderDate`, and then sum the `TotalAmount`. However, the resulting collection seems to contain duplicate groups where the `TotalAmount` is not being aggregated correctly. Here’s the query I’m using: ```csharp var groupedOrders = context.Orders .GroupBy(o => new { o.CustomerName, o.OrderDate.Date }) .Select(g => new { CustomerName = g.Key.CustomerName, OrderDate = g.Key.OrderDate, TotalAmount = g.Sum(o => o.TotalAmount) }) .ToList(); ``` When I run this code, I notice that the `TotalAmount` is summed up correctly, but the output still includes multiple entries for the same `CustomerName` and `OrderDate`. For example: ``` CustomerName | OrderDate | TotalAmount --------------|-------------|------------- John Doe | 2021-09-01 | 100.00 John Doe | 2021-09-01 | 150.00 Jane Doe | 2021-09-02 | 200.00 ``` I’ve ensured that there aren't any duplicate entries in the database. I also tried adding a `Distinct()` after grouping, but that didn't help either. Is there something I'm missing in my LINQ query that would cause this behavior? Any insights on how to properly group and aggregate without getting these duplicates would be greatly appreciated! What am I doing wrong? Is there a better approach? Is this even possible? This is for a web app running on Debian. Cheers for any assistance!