如何刪除linq查詢中的可重複項目

Question

listOrders.DataSource = (from sp in dbdata.Specifications 
         join ord in dbdata.Orders on sp.O_id equals ord.O_id 
         join prd in dbdata.Products on ord.O_id equals prd.O_ID 
         where sp.Approve == "Yes" && 
         sp.Awailable_BOM == "Yes" && 
         prd.Hours_prd == null 
         orderby sp.O_id descending 
         select sp.O_id).Distinct(); 

在這裏我正在努力獲得下降值。但它總是會提升價值。如果我刪除「Distinct（）」，它會正常工作，但添加「Distinct（）」後會發生此問題。

Answer 1

試試這個：

listOrders.DataSource = (from sp in dbdata.Specifications 
         join ord in dbdata.Orders on sp.O_id equals ord.O_id 
         join prd in dbdata.Products on ord.O_id equals prd.O_ID 
         where sp.Approve == "Yes" && 
         sp.Awailable_BOM == "Yes" && 
         prd.Hours_prd == null 
         select sp.O_id).Distinct().OrderByDescending();