c# - LINQ- 'the type of one of the expressions in the join clause is incorrect'

Question

我有一个复杂的 LINQ to SQL 查询，它连接到两个表上 - 一个相当简单并且工作正常，但一个相当复杂并且我得到 连接中表达式之一的类型条款不正确。调用“GroupJoin

时类型推断失败

这是一个相当长的查询，我正在开发一项可以访问 Internet 的工作，所以我想看看似乎是问题的行是否足够:

join consignments in dc.Consignments
    .FirstOrDefault(x => x.TripDate > dateFrom 
    && x.TripDate < dateTo 
    && x.DeliveryDepot == depot.Letter 
    && (x.DeliveryStatus == 2 || x.DeliveryStatus == 3))
  on new { Reg = s.VehicleReg, Depot = s.VehicleDepot } 
      equals new { Reg = consignments.VehicleReg, Depot = consignments.DeliveryDepot }
  into con

我已经确保数据类型相同，但还是不行。有什么想法吗？

Answer 1

您确定 a.Vehicle Depot 与 consignments.Delivery Depot 的类型相同吗？

on new { Reg = s.VehicleReg, Depot = s.VehicleDepot } 
equals new { Reg = consignments.VehicleReg, Depot = consignments.DeliveryDepot }