Question

我的数据如下：

 read_date |  T1  |  T2  |
15.02.2000 |   2  |   3  |
16.02.2000 |   4  |   5  |
15.03.2000 |   2  |   3  |
16.03.2000 |   5  |   4  |

我希望获得T1和T2的总和，如下所示：

 read_date |  T1  |  T2  |
   02.2000 |   6  |   8  |
   03.2000 |   7  |   7  |

我尝试写这样的东西：

var result = from s in meter_readings.Take(10)
             group s by new { s.read_date} into g
             select new
             {
                 read_date = g.Key.read_date,
                 T1 = g.Sum(x => x.T1),
                 T2 = g.Sum(x => x.T2)
             };

但这并没有给出预期的数据。是否有任何例子可以提供每小时数据，每日总和等数据。

由于

Answer 1

分组时，您应该只考虑年份和月份：

var result = 
    from s in  meter_readings.Take(10)
    group s by new { date = new DateTime(s.read_date.Year, s.read_date.Month, 1) } into g
    select new
    {
        read_date = g.Key.date,
        T1 = g.Sum(x => x.T1),
        T2 = g.Sum(x => x.T2)
    };

Answer 2

首先，我认为你可以跳过匿名类型：

var result = from s in meter_readings.Take(10) 
         group s by s.read_date into g 
         select new 
         { 
             read_date = g.Key, 
             T1 = g.Sum(x => x.T1), 
             T2 = g.Sum(x => x.T2) 
         };

其次，要按月分组，请使用一些唯一标识月份的值，如下所示：

var result = from s in meter_readings.Take(10) 
         group s by s.read_date.ToString("yyyy.MM") into g 
         select new 
         { 
             read_month = g.Key, 
             T1 = g.Sum(x => x.T1), 
             T2 = g.Sum(x => x.T2) 
         };

Answer 3

您当前的分组将按完整日期分组（即15.02.2000而不是02.2000）。这将最终为每一天创造一个单独的团体，而不是一个月。

将一个.Month添加到组中（假设它是一个日期对象）：

group s by new { s.read_date.Month} into g

Answer 4

    static void Main()
    {
        var list = new List<meter_reading>
                       {
                           new meter_reading {Date = new DateTime(2000, 2, 15), T1 = 2, T2 = 3},
                           new meter_reading {Date = new DateTime(2000, 2, 10), T1 = 4, T2 = 5},
                           new meter_reading {Date = new DateTime(2000, 3, 15), T1 = 2, T2 = 3},
                           new meter_reading {Date = new DateTime(2000, 3, 15), T1 = 5, T2 = 4}
                       };
            var sum = list
            .GroupBy(x => GetFirstDayInMonth(x.Date))
            .Select(item => new meter_reading
                                {
                                    Date = item.Key,
                                    T1 = item.Sum(x => x.T1),
                                    T2 = item.Sum(x => x.T2),
                                }).ToList();
    }

    private static DateTime GetFirstDayInMonth(DateTime dateTime)
    {
        return new DateTime(dateTime.Date.Year, dateTime.Date.Month, 1);
    }

Answer 5

query.OrderBy(o => o.OrderDate)
                .GroupBy(o => DbFunctions.CreateDateTime(o.OrderDate.Year, o.OrderDate.Month, 1, 0, 0, 0))
                       .Select(group => new DateIncomeDto { Date = group.Key.Value, Income = group.Sum(item => item.PayFee ?? 0) });

它对我有用！

Linq按日期获取数据组的总和

5 个答案: