LINQ SELECT TAKE 1每行

Question

我怎樣才能選擇1只LINQ中的每個數據列，只返回1行。因爲當我穿上。取（1）只有1行的結果會出現，但我想有不同的入口2行的結果

，使其在這裏明確就是我的意思

在C＃

，這裏是我的查詢

using (PharmacyDBEntities entities = new PharmacyDBEntities()) 
     { 
      var positem = (from a in entities.POSEntries.Take(1) 
          where a.Invoice.AccountID == authLogin.userid && a.Invoice.InvoiceStatusID == 1 
          select new 
          { 
           a.Item.ItemCode, 
           a.Item.Name, 
           Quantity = (from b in entities.POSEntries where b.Invoice.AccountID == authLogin.userid && b.Invoice.InvoiceStatusID == 1 select b).Count(), 
           a.Item.SellingPrice 
          }).ToList(); 
      gcItemList.DataSource = positem; 
     } 

而結果

有任何建議傢伙？會對我有很大的幫助。謝謝

Answer 1

所以，你想要Distinct（）而不是Take（1）？沿着這些路線的東西：

var positem = (from a in entities.POSEntries 
    where a.Invoice.AccountID == authLogin.userid && a.Invoice.InvoiceStatusID == 1 
         select new 
         { 
          a.Item.ItemCode, 
          a.Item.Name, 
          Quantity = (from b in entities.POSEntries where b.Invoice.AccountID == authLogin.userid && b.Invoice.InvoiceStatusID == 1 select b).Count(), 
          a.Item.SellingPrice 
         }).Distinct().ToList(); 

Answer 2

只返回前n個元素。我認爲你需要嘗試使用Distinct方法。

Answer 3

您可以使用LINQ GroupBy

var positem = entities.POSEntries.Where(a=> a.Invoice.AccountID == authLogin.userid && a.Invoice.InvoiceStatusID == 1) 
       .GroupBy(x=>x.Item.ItemCode).Select(g=> new { 
           g.Key, 
           g.First().Item.Name, 
           Quantity = g.Count(), 
           g.First().Item.SellingPrice 
          }).ToList();