Question

给出以下行：

Amount, Name, Id
   Scenario 1: 100.00,ABC,101
              -100.00,ABC,101

   Scenario 2: 50.00,XYZ,123
              -100.00,XYZ,123

我想仅在金额未总计为0.00金额时对行进行求和和分组。所以Linq查询应该返回：

Amount, Name, Id
Scenario 1: 100.00,ABC,101
           -100.00,ABC,101

Scenario 2:-50.00,XYZ,123

到目前为止我所拥有的：

var results = dt.AsEnumerable().GroupBy(row => new
{
   Name = row.Field<string>("NAME"),
   Id = row.Field<int>("ID")
}).Select(grp =>
{
   DataRow dr = dt.NewRow();
   dr["AMOUNT"] = grp.Sum(r => r.Field<decimal>("AMOUNT"));
   dr["NAME"] = grp.Key.Name;
   dr["ID"] = grp.Key.Id;
   return dr;
}).CopyToDataTable();

Answer 1

您可以使用SelectMany扩展程序尝试以下查询：

Answer 2

很难理解你的要求，所以我假设你的意思是：

汇总和分组行，因此只列出任何给定ID的汇总事务，除非总数为零，然后列出该ID的所有事务。

这是一个工作示例，包含您提供的测试数据：

var amounts = new[]
{
   new 
   {
       Amount = 100.00m,
       Name = "ABC",
       Id = 101,
   },
   new
   {
       Amount = -100.00m,
       Name = "ABC",
       Id = 101,
   },
   new
   {
       Amount = 50.00m,
       Name = "XYZ",
       Id = 123,
   },
   new
   {
       Amount = -100.00m,
       Name = "XYZ",
       Id = 123,
   },
};

// summarise everything
var summaries = from a in amounts
                group a by new { a.Id, a.Name } into grouping
                select new
                {
                    Amount = grouping.Sum(g => g.Amount),
                    grouping.Key.Name,
                    grouping.Key.Id,                    
                };

// get the ids of records we need the full audit log for
var zeroSummaries = summaries.Where(s => s.Amount == 0).Select(s => s.Id).ToList();

// concat the summarised records together with the ones we need the full audit log for
summaries = amounts.Where(a => zeroSummaries.Contains(a.Id))
                   .Concat(summaries.Where(s => s.Amount != 0));

这是输出：

如果列总计不为零，则LINQ仅对行进行求和

2 个答案: