按ID和合计数量合并C# Linq

// 假设有一个包含ID和数量的数据集合
List<DataItem> data = new List<DataItem>
{
    new DataItem { ID = 1, Quantity = 10 },
    new DataItem { ID = 2, Quantity = 5 },
    new DataItem { ID = 1, Quantity = 3 },
    new DataItem { ID = 2, Quantity = 8 },
    new DataItem { ID = 3, Quantity = 2 }
};

// 使用LINQ按ID和合计数量合并
var result = data.GroupBy(item => item.ID)
                 .Select(group => new
                 {
                     ID = group.Key,
                     TotalQuantity = group.Sum(item => item.Quantity)
                 });

// 输出结果
foreach (var item in result)
{
    Console.WriteLine($"ID: {item.ID}, Total Quantity: {item.TotalQuantity}");
}

ID: 1, Total Quantity: 13
ID: 2, Total Quantity: 13
ID: 3, Total Quantity: 2