Linq To SQL LEFT OUTER JOIN (Left Join)

SQL:

SELECT [t0].[ProductName], [t1].[TotalPrice] AS [TotalPrice]
FROM [Product] AS [t0]
LEFT OUTER JOIN [OrderDetail] AS [t1] ON [t0].[ProductID] = [t1].[ProductID] 

Linq Query:

from p in Products
join od in OrderDetails on p.ProductID equals od.ProductID into uio
from o in uio.DefaultIfEmpty()
select new { p.ProductName, o.TotalPrice }


Linq Method:

 Products
   .GroupJoin (
      OrderDetails, 
      p => p.ProductID, 
      od => od.ProductID, 
      (p, uio) => 
         new  
         {
            p = p, 
            uio = uio
         }
   )
   .SelectMany (
      temp0 => temp0.uio.DefaultIfEmpty (), 
      (temp0, o) => 
         new  
         {
            ProductName = temp0.p.ProductName, 
            TotalPrice = o.TotalPrice
         }
   )

 

转载于:https://www.cnblogs.com/huangyoum/p/4617036.html