linq中的子查詢

Question

在linq中編寫這個查詢的最佳方式是什麼？

SELECT * 
    FROM product_master 
    where product_id in (select product_id from product where buyer_user_id=12) 

Answer 1

var _result = from a in product_master 
       where (product.Where(s => s.buyer_user_id == 12)) 
         .Contains(a.product_ID) 
       select a; 

或

var _result = (from a in product_master 
       join b in product 
        on a.product_id equals b.product_id 
       where b.buyer_user_id == 12 
       select a).Distinct(); 

Answer 2

JW的答案是正確的。另外，考慮到子查詢不相關，你可以單獨表達出來：

var pids = product.Where(p => p.buyer_user_id == 12); 
var r = product_master.Where(pm => pids.Contains(pm.product_id));