Geek asks and answers

Left Outer Join Linq to Objects / SQL

How can I write the following SQL in LINQ for Entities?

SELECT r.rolename,
       ( CASE
           WHEN ur.username IS NULL THEN 0
           ELSE 1
         END ) AS isinrole
FROM   bgt.roles r
       LEFT OUTER JOIN bgt.usersinroles ur
         ON ur.rolename = r.rolename
            AND ur.username = 'ADMIN'
+3
source share
2 answers

It worked for me. Thanks for all the suggestions.

var query = 
from r in Roles
from ur in UsersInRoles
.Where(v => v.Rolename == r.Rolename && v.Username == "ADMIN")
.DefaultIfEmpty()
select new { Rolename = r.Rolename, IsInRole = (ur.Username != null) };

The generated SQL is as follows

SELECT 
1 AS [C1], 
[Extent1].[Rolename] AS [Rolename], 
CASE WHEN ([Extent2].[Username] IS NOT NULL) THEN cast(1 as bit) WHEN ([Extent2].[Username] IS NULL) THEN cast(0 as bit) END AS [C2]
FROM  [bgt].[Roles] AS [Extent1]
LEFT OUTER JOIN [bgt].[UsersInRoles] AS [Extent2] ON ([Extent2].[Rolename] = [Extent1].[Rolename]) AND ('ADMIN' = [Extent2].[Username])
+3
source

I would do it like this:

from role in db.Roles
let isInRole = role.UsersInRoles.Any(u => u.UserName == "ADMIN")
select new { role.RoleName, isInRole }

Although the generated SQL is not as good as yours.

+2
source

More articles:


All Articles