EF 核心加入多个 OR 条件

Question

我想将此 sql 查询转换为 linq :

select * from  A a
join B b on (    (a.level1= b.PerimeterID and  b.PerimeterLevelID = 1)
              OR (a.level2= b.PerimeterID and  b.PerimeterLevelID = 2)
              OR (a.level3= b.PerimeterID and  b.PerimeterLevelID = 3)
            )

我尝试了什么：

from a in A
join b in B on new {PerimeterID = a.level1, PerimeterLevelID = 1 } equals new { b.PerimeterID, b.PerimeterLevelID }
where (a.level2 == b.PerimeterID && b.PerimeterLevelID == 2) ||
      (a.level3 == b.PerimeterID && b.PerimeterLevelID == 3)

它生成此 sql 查询：

select * from  A a
join B b on (a.level1= b.PerimeterID and  b.PerimeterLevelID = 1)
where (a.level2= b.PerimeterID and  b.PerimeterLevelID = 2)
       OR (a.level3= b.PerimeterID and  b.PerimeterLevelID = 3))

我也试过 Linqer 但它无法将 OR 转换为 linq

SQL cannot be converted to LINQ: OR

我需要做什么才能转换此 sql 查询

Answer 1

你可以试试 DefaultIfEmpty()。使用此命令连接将表现得像左连接

from a in A
from b in B.DefaultIfempty()
where (   (a.level1== b.PerimeterID &&  b.PerimeterLevelID == 1)
       || (a.level2== b.PerimeterID &&  b.PerimeterLevelID == 2)
       || (a.level3== b.PerimeterID &&  b.PerimeterLevelID == 3))

Answer 2

内部联接等同于过滤交叉联接。那么

怎么样

from a in A
from b in B 
where (a.level1 == b.PerimeterID && b.PerimeterLevelID == 1) ||
      (a.level2 == b.PerimeterID && b.PerimeterLevelID == 2) ||
      (a.level3 == b.PerimeterID && b.PerimeterLevelID == 3)
select new {a,b};

?

Answer 3

我认为这个查询会有所帮助

var query = from a in context.A
            join b1 in context.B
                on new { Perimeter = a.level1, LevelID = 1 }
                equals new { Perimeter = b1.PerimeterID, LevelID = b1.PerimeterLevelID }
            join b2 in context.B
                on new { Perimeter = a.level2, LevelID = 2 }
                equals new { Perimeter = b2.PerimeterID, LevelID = b2.PerimeterLevelID }
            join b3 in context.B
                on new { Perimeter = a.level3, LevelID = 3 }
                equals new { Perimeter = b3.PerimeterID, LevelID = b3.PerimeterLevelID }
            select new
            {
                a,
                b1,
                b2,
                b3
            };