將T-SQL轉換為LINQ Lambda

Question

如果需要，如何用LINQ lambda表達式或查詢語法編寫此查詢？ 我已經嘗試了一段時間了。 多次連接使它變得困難。 該聯接的總記錄超過2000，最終結果應為15條記錄

select 
    year([date]), 
    month([date]),
    sum(ot.rate)
from s as s 
join cs cs on cs.s_id= s.id
join ot ot on ot.id = cs.o_id
group by
    year([date]), 
    month([date])

這是我所獲得的最接近的，但不會編譯。 我無法從select塊中訪問ot屬性。

    var query = from se in table_se
        join cs in table_cs on se.Id equals cs.S_Id
        join ot in table_ot on cs.O_Id equals ot.Id
        group se by new { se.Date.Year, se.Date.Month } into grp 
        select new
        {
            grp.Key.Year,
            grp.Key.Month,
            grp.Sum(ot.Rate)
        };

Answer 1

您非常接近Enumerable.Sum帶有謂詞

var query = from se in table_se
        join cs in table_cs on se.Id equals cs.S_Id
        join ot in table_ot on cs.O_Id equals ot.Id
        group ot by new { se.Date.Year, se.Date.Month } into grp 
        select new
        {
            Year = grp.Key.Year,
            Month = grp.Key.Month,
            Sum = grp.Sum(x => x.Rate)
        };