Linq to SQL計算查詢中一組項目的百分比

Question

Linq SQL的新手和SQL的新手。 第一篇文章，所以請保持溫柔。
我有一些類似於下表的內容，我正在根據C＃中的日期范圍查詢到dataGridView中。

熱號費用號重量DOB

1            1              500     8/26/15
1            2              3500    8/26/15
1            3              2200    8/26/15
2            1              2000    8/27/15
2            2              1100    8/27/15

---

var query = from SU in dct.GetTable<ScrapInCharge>()
                        where ((SU.DOB >= dateTimePicker2.Value.Date) &&
                               (SU.DOB <= dateTimePicker1.Value.Date))
                        orderby SU.HeatNumber descending
                        select SU;
            scrapInChargeBindingSource.DataSource = query;

我需要添加一列，以顯示每個ChargeNumber占HeatNumber總重量的百分比。 我確實知道如何通過HeatNumber獲得每個熱量的總重量。

var TotalHeatWgt = from a in dct.ScrapInCharges
                           where ((a.DOB >= dateTimePicker2.Value.Date) &&
                               (a.DOB <= dateTimePicker1.Value.Date))
                           group a.Weight by a.HeatNumber
                               into b
                               select new { HeatNumber = b.Key, TotalWgt = b.Sum() };

我目前仍停留在如何將其合並到單個C＃查詢中，在weight列之后插入％Heat列的問題上。 可以做到這一點，還是我需要向Heat的dataGridView％添加未綁定的列，並使用我的TotalHeatWgt查詢的返回值遍歷行？

Answer 1

簡單嘗試：

var results = data.Select(d => new {
    d.HeatNumber,
    d.ChargeNumber,
    d.Weight,
    Percent = 100.0 * d.Weight / data.Where(dd => dd.HeatNumber == d.HeatNumber).Sum(dd => dd.Weight)
});

要么

from row in data
select new { 
    row.HeatNumber,
    row.ChargeNumber,
    row.Weight,
    Percent = 100.0 * row.Weight / (from innerRow in data
                                        where innerRow.HeatNumber == row.HeatNumber
                                        select innerRow.Weight
                                    ).Sum()
};

下面的代碼將具有更高的性能（至少在內存中，我不確定在SQL中是否會更好）：

var results = data.GroupBy (d => d.HeatNumber)
    .SelectMany (grp => grp.Select(row => new {
        row.HeatNumber,
        row.ChargeNumber,
        row.Weight,
        Percent = 100.0 * row.Weight / grp.Sum(dd => dd.Weight)
    })
); 

並使用查詢語法：

from row in data 
group row by row.HeatNumber into grp
from innerRow in grp
select new { 
    innerRow.HeatNumber,
    innerRow.ChargeNumber,
    innerRow.Weight,
    Percent = 100.0 * innerRow.Weight / grp.Sum(dd => dd.Weight)
};

他們都打印以下結果：

HeatNumber    ChargeNumber     Weight  Percent 
1             1                500     8.06451612903226 
1             2                3500    56.4516129032258 
1             3                2200    35.4838709677419 
2             1                2000    64.5161290322581 
2             2                1100    35.4838709677419 

那是你追求的嗎？ 為了簡單起見，我省略了按日期進行過濾，因為實際問題出在那之后