Issue with LINQ Query Returning Unexpected Results When Using GroupBy in C# 9
I've been banging my head against this for hours. I'm encountering a strange issue when trying to group data using LINQ in C# 9. I have a list of orders, and I want to group them by customer ID and then sum the total amount spent by each customer. However, the resulting groups don't seem to reflect the correct totals. Here's the code I've written: ```csharp public class Order { public int CustomerId { get; set; } public decimal Amount { get; set; } } var orders = new List<Order> { new Order { CustomerId = 1, Amount = 100 }, new Order { CustomerId = 2, Amount = 200 }, new Order { CustomerId = 1, Amount = 50 }, new Order { CustomerId = 2, Amount = 150 } }; var groupedOrders = orders.GroupBy(o => o.CustomerId) .Select(g => new { CustomerId = g.Key, TotalAmount = g.Sum(o => o.Amount) }); foreach (var group in groupedOrders) { Console.WriteLine($"Customer ID: {group.CustomerId}, Total Amount: {group.TotalAmount}"); } ``` When I run this code, I expect to see: - Customer ID: 1, Total Amount: 150 - Customer ID: 2, Total Amount: 350 But instead, I'm seeing the following output: - Customer ID: 1, Total Amount: 100 - Customer ID: 2, Total Amount: 200 I double-checked my data, and it seems correct. I've also tried using `ToList()` before the `GroupBy` to ensure that I'm working with a complete collection, but that didn’t help. Is there something I'm missing here or a subtle issue with how the grouping is occurring in my LINQ query? Any insights would be appreciated! My development environment is Windows. I've been using C# for about a year now.