ling to sql创建临时变量 let的使用

　　使用let赋值给临时变量

var dailys = from f in _postgreDbContext.draws
                                         let temp = f.review_time.Value.Date
                                         where f.time_Data != null && f.time_Data == temp 
                                         group f by new { f.id, f.time_Data } into g
                                         select new
                                         {
                                             Date = g.Key.time_Data,
                                             g.Key.id,
                                             draws_money = g.Sum(m => m.money)
                                         };