使用联接运算符，只能执行相等联接。其他类型的连接可以使用其他操作符构造。我不确定使用这些方法或更改where子句是否会更容易执行您试图执行的确切连接。关于join子句的文档可以在这里找到。MSDN有一篇关于连接操作的文章，其中还有指向其他连接示例的多个链接。

使用匿名类型的解决方案应该可以正常工作。LINQ只能表示等连接(使用连接子句)，实际上，这正是您根据原始查询想要表达的内容。

如果您因为某些特定的原因而不喜欢匿名类型的版本，那么您应该解释这个原因。

如果你想做的事情与你最初要求的不同，请举例说明你真正想做的事情。

编辑:回答问题中的编辑:是的，要做一个“日期范围”连接，你需要使用一个where子句。它们在语义上是等效的，所以这只是一个可用的优化问题。等连接提供了简单的优化(在LINQ到对象中，包括LINQ到数据集)，通过创建基于内部序列的查找-可以将其视为从键到匹配该键的条目序列的哈希表。

Doing that with date ranges is somewhat harder. However, depending on exactly what you mean by a "date range join" you may be able to do something similar - if you're planning on creating "bands" of dates (e.g. one per year) such that two entries which occur in the same year (but not on the same date) should match, then you can do it just by using that band as the key. If it's more complicated, e.g. one side of the join provides a range, and the other side of the join provides a single date, matching if it falls within that range, that would be better handled with a where clause (after a second from clause) IMO. You could do some particularly funky magic by ordering one side or the other to find matches more efficiently, but that would be a lot of work - I'd only do that kind of thing after checking whether performance is an issue.

您可以这样做(如下所示)

var query = from p in context.T1

        join q in context.T2

        on

        new { p.Col1, p.Col2 }

        equals

         new { q.Col1, q.Col2 }

        select new {p...., q......};

如果字段名在实体中不相同

var result = from x in entity
   join y in entity2 on 
          new {
                field1=   x.field1,
               field2 =  x.field2 
             } 
          equals
         new { 
                field1= y.field1,
                field2=  y.myfield
              }
select new {x,y});

我认为一个更具可读性和灵活性的选项是使用Where函数:

var result = from x in entity1
             from y in entity2
                 .Where(y => y.field1 == x.field1 && y.field2 == x.field2)

这也允许通过添加. defaultifempty()轻松地将内连接更改为左连接。

from d in db.CourseDispatches
                             join du in db.DispatchUsers on d.id equals du.dispatch_id
                             join u in db.Users on du.user_id equals u.id
                             join fr in db.Forumreports on (d.course_id + '_' + du.user_id)  equals  (fr.course_id + '_'+ fr.uid)

这对我很有用