c# - LINQ 查询以显示 2 个表的结果

Question

这是我的两张桌子

买股

出售股份

我想要的 LINQ 查询的结果表是

此结果表包含公司名称以及总买卖股份。

到目前为止，我的代码是：

var userHistoryAll = from buy in db.share_bought_history
                     join sold in db.share_sold_history
                     on buy.regist_id equals sold.regist_id
                     select new
                             {
                                 buy,
                                 sold
                             } into combine
                     group combine by combine.buy.comapnay_id
                     into final
                     select new
                             {
                                 cName = final.FirstOrDefault().buy.company.company_name,
                                 uBuy = final.Sum(x => x.buy.no_of_sahre),
                                 uSold = final.Sum(x => x.sold.no_of_sahre)
                             };

但我无法得到想要的结果。

Answer 1

尝试以下：

var userHistoryAll = (from buy in db.share_bought_history
                                 join sold in db.share_sold_history
                                 on buy.comapnay_id equals sold.comapnay_id
                                 select new { buy = buy, sold = sold})
                                 .GroupBy(x => x.buy.comapnay_id)
                                 .Select(x => new {
                                     cName=x.Key,
                                     uBuy = x.Select(y => y.buy.no_of_sahre).Sum(),
                                     uSold = final.Select(y => y.sold.no_of_sahre).Sum()
                                 }).ToList(); 

Answer 2

问题是您的数据没有唯一的键加入（至少这是我的观点）

所以先让 groub 然后加入

我个人更喜欢 lambda 语法，但你可以转换它

var buyGroub = BuyShare.GroubBy(x=>x.Id)
                       .Select(x=> new 
                       {
                          name = x.Name,
                          buy = x.Sum(s => s.Share)
                       }

var soldGroub = SoldShare.GroubBy(x=>x.Id)
                       .Select(x=> new 
                       {
                          name = x.Name,
                          sold = x.Sum(s => s.Share)
                       }

现在你可以随心所欲地呈现

var result = buyGroub.Join(soldGroub,
                          a=>a.name,
                          b=>b.name,
                          (a,b)=>new {a.Name , a.buy , b.sold});

编辑

要获取 list1 中而不是 list2 中的记录，反之，您需要执行一个名为full external join的操作。检查接受的答案，它有两个数组，相当于您的 2 个列表