LINQ-嵌套查询

小编典典

LINQ-嵌套查询

sql

我有一个SQL语句，我试图将其转换为LINQ查询。我需要执行此操作，因为我无法编辑数据库:(。无论如何，我都有一条如下所示的SQL语句：

SELECT
  CustomerID,
  FirstName,
  LastName,
  Gender,
  BirthMonth,
  (SELECT COUNT(ID) FROM PurchaseOrder WHERE [CustomerID]=CustomerID) as TotalPurchases
FROM
  MyEntities

我知道如何在LINQ中完成除嵌套查询部分之外的所有操作。目前，我有以下内容：

var results = from x in context.MyEntities 
              select new Customer() 
              { 
                CustomerID = x.CustomerID, 
                FirstName = x.FirstName, 
                LastName = x.LastName, 
                Gender = x.Gender, 
                BirthMonth = x.BirthMonth,
                TotalPurchases = ? 
              };

如何在LINQ中执行嵌套查询以获取TotalPurchases的值？

太感谢了！

阅读 206

2021-04-14

共1个答案

小编典典

您也可以嵌套Linq to Entities查询：

var results = from x in context.MyEntities 
              select new Customer() 
              { 
                CustomerID = x.CustomerID, 
                FirstName = x.FirstName, 
                LastName = x.LastName, 
                Gender = x.Gender, 
                BirthMonth = x.BirthMonth,
                TotalPurchases = context.PurchaseOrders
                                        .Where(po=>po.CustomerId == x.CustomerId)
                                        .Count()
              };

2021-04-14