Linq的大于条件加盟 [英] Greater Than Condition in Linq Join

问题描述

我试图有条件地连接两个表，但这给了我语法错误.我试图在网络中找到解决方案，但我找不到如何用条件进行条件联接.唯一的另一种选择是首先从一个表中获取值，然后再次进行查询.

I had tried to join two table conditionally but it is giving me syntax error. I tried to find solution in the net but i cannot find how to do conditional join with condition. The only other alternative is to get the value first from one table and make a query again.

我只想确认是否还有其他方法可以使用linq进行条件连接.

I just want to confirm if there is any other way to do conditional join with linq.

这是我的代码，我试图找到所有等于或低于我的位置.基本上，我想得到我的同辈和下属.

Here is my code, I am trying to find all position that is equal or lower than me. Basically I want to get my peers and subordinates.

from e in entity.M_Employee
join p in entity.M_Position on e.PostionId >= p.PositionId
select p;

推荐答案

使用LINQ连接无法做到这一点-LINQ仅支持 equijoins .但是，您可以这样做:

You can't do that with a LINQ joins - LINQ only supports equijoins. However, you can do this:

var query = from e in entity.M_Employee
            from p in entity.M_Position
            where e.PostionId >= p.PositionId
            select p;

或者稍微替代但等效的方法:

Or a slightly alternative but equivalent approach:

var query = entity.M_Employee
                  .SelectMany(e => entity.M_Position
                                      .Where(p => e.PostionId >= p.PositionId));

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