如何在Entity Framework中使用'In'SQL关键字？

Question

这是我的SQL命令

SELECT KEY,NAME 
from COMPANY c 
WHERE  KEY IN (select KEY from USER_COMPANY where UserId = @UserId) 
order by NAME asc 

所以我想将其转换为实体框架。

我尝试这样

var userCompany = (from u in db.USER_COMPANY 
         where u.UserId == UserId 
         select(u.KEY)); 

      var user = (from c in db.COMPANY 
         where (c => userCompany.Contains(c.KEY) 
         select c); 

，但它无法正常工作。

如何在Entity Framework中使用SQL IN关键字？

Answer 1

试试这个：

var query = from c in db.COMPANY 
      where (from u in db.USER_COMPANY 
        where u.UserId == UserId 
        select u.KEY).Contains(c.KEY) 
      orderby c.NAME 
      select c.KEY, c.NAME; 

Answer 2

我的理解是，从.Contains()到IN的翻译只是刚添加到EF6中。

根据此工作项目（http://entityframework.codeplex.com/workitem/245）和发行说明：改进了LINQ查询中Enumerable.Contains的性能。

因此，在EF6中查找它

Answer 3

您可以使用实体框架执行原始SQL查询。看看这个链接：http://msdn.microsoft.com/en-us/data/jj592907.aspx

Answer 4

注意，该SQL查询具有完全相同的含义：

SELECT c.KEY, c.NAME 
FROM COMPANY c 
JOIN (SELECT DISTINCT KEY FROM USER_COMPANY where UserId = @UserId) u 
ON U.KEY = C.KEY 
ORDER BY c.NAME asc 

所以，你应该能够只是做：

var userCompany = (from u in db.USER_COMPANY 
        where u.UserId == UserId 
        select(u.KEY)).Distinct(); 

var result = from c in db.COMPANY 
      join u in userCompany 
      on c.KEY = u.KEY 
      select new {c.KEY, c.NAME};