LINQ to SQL：orderby 求和运算

Question

我有一个表，我需要根据 group by 子句对数字列求和来排序结果集。

例如，该表包含销售人员 ID、订单号和订单价值。我想要一份按累计订单价值排列的前 10 名顶级销售人员名单。

SQL 和 LINQ 新手，因此任何建议将不胜感激！

Answer 1

var results = context.Sales.GroupBy(s => s.SalesPersonID)
                           .Select(g => new {
                                              SalesPersonID = g.Key, 
                                              Sales = g.Sum(s => s.OrderValue) 
                                             })
                           .OrderByDescending(r => r.Sales)
                           .Take(10);

Answer 2

像这样的东西：

var orders = new[]
{
    new Order { SalesPersonId = 1, OrderNumber = 1, OrderValue = 1 },
    new Order { SalesPersonId = 1, OrderNumber = 2, OrderValue = 2 },
    new Order { SalesPersonId = 2, OrderNumber = 2, OrderValue = 2 },
};

var topSalesMen = orders
    .GroupBy(arg => arg.SalesPersonId)
    .Select(arg => new { SalesPersonId = arg.Key, TotalOrderValue = arg.Sum(x => x.OrderValue) })
    .OrderByDescending(arg => arg.TotalOrderValue)
    .Take(10)
    .ToList();