c# - LINQ 按特定列中每个唯一值的最高值排序

Question

我正在尝试弄清楚如何使用 linq 在名为 bids 的表中选择领先的出价。

结果需要对每个唯一的userId取最高出价，并按bidValue排序显示

出价表:

bidId 1, userid 1, bidValue = 10
bidId 2, userid 2, bidValue = 20
bidId 3, userid 3, bidValue = 20
bidId 4, userid 1, bidValue = 30
bidId 5, userid 2, bidValue = 40
bidId 6, userid 1, bidValue = 50

结果:

bidId 6, userid 1, bidValue 50
bidId 5, userid 2, bidValue 40
bidId 3, userid 3, bidValue 20

Answer 1

像这样的东西应该可以工作

var query = (from bid in context.Bids
            group bid by bid.userid into bidg
            select new
            {
               bidId = bidg.OrderByDescending(b => b.bidValue).First().bidid,
               userid = bidg.Key,
               bidValue = bidg.Select(b => b.bidValue).Max()
            }).OrderByDescending(b => b.bidvalue);