Entity Framework 中连接子句中的一个表达式的类型不正确。左连接中的常量

Question

我正在尝试在 EF 查询中进行左联接。我收到以下错误：

Error CS1941 The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'GroupJoin'

这是 C# 代码：

var foo = from m in db.ClientMasters
                      join a in db.Orders on new { m.Id, Status = "N" } equals new { a.ClientID, a.Status } into a_join
                      from a in a_join.DefaultIfEmpty()
                      select new { m.ClientID, a.ID };

Answer 1

连接中的列名必须匹配；这是更正后的代码：

var foo = from m in db.ClientMasters
                      join a in db.Orders on new { ClientID = m.Id, Status = "N" } equals new { a.ClientID, a.Status } into a_join
                      from a in a_join.DefaultIfEmpty()
                      select new { ClientID = m.Id, OrderId = a.Id };

Entity Framework 中连接子句中的一个表达式的类型不正确。左连接中的常量

The type of one of the expressions in the join clause is incorrect in Entity Framework. Constant in left join

c#

sql-server

entity-framework

join

linq-to-sql