CODEWITHSUNDEEP
c#sqllinqentity-framework-4
Carel
Carel

Reputation: 2143

Linq with Lambda equivalent of SQL

I am relatively new to entity framework and I've been trying to write a Linq statement with Lambda that includes a simple join. I have three tables: Staff - StaffRole - Role.

Partial Diagram

I want a staff member in a certain role that satisfies a certain condition. Its very simple to write this in regular SQL:

SELECT *
FROM Staff s
INNER JOIN StaffRole sr ON s.StaffId = sr.StaffId
INNER JOIN Role r ON sr.RoleId = r.RoleId
WHERE r.Description = 'SpecialisedHealthManager'
AND s.PrimaryShm = 0

Now, writing it in a Linq statement has not given me much luck. I'm thinking it would be something like this:

var actingShm = db.Staff.Join(db.StaffRole,
                           inner => inner.StaffId,
                           outer => outer.Role,
                           (outer, inner) => new
                           {
                               StaffId = inner.StaffId,
                               FirstName = inner.Staff.FirstName,
                               Surname = inner.Staff.Surname,
                               SamAccountName = inner.Staff.SamAccountName,
                               RoleId = outer.Description
                           });

Needless to say, this is not working..

Upvotes: 4

Views: 352

Answers (3)

user3401335
user3401335

Reputation: 2405

Try using it this way:

var list = from s in Staff
join sr in StaffRole on s.StaffId equals sr.StaffId
join r in Role on sr.RoleId equals r.RoleId
where r.Description == 'SpecialisedHealthManager' && s.PrimaryShm == 0
select new
{
   StaffId = s.StaffId,
   FirstName = s.Staff.FirstName,
   Surname = s.Staff.Surname, 
   SamAccountName = s.Staff.SamAccountName,
   RoleId = r.Description
});

Upvotes: 3

Aron
Aron

Reputation: 15772

You should have your associations setup so you can do this...

var actingShm = from s in db.Staff
                from r in s.Roles
                where r.Description == "SpecialisedHealthManager"
                select new
                       {
                           StaffId = s.StaffId,
                           FirstName = s.FirstName,
                           Surname = s.Surname,
                           SamAccountName = s.SamAccountName,
                           RoleId = r.Description
                       });

Are you using Entity Framework or Linq2SQL?

Upvotes: 1

GrzegorzM
GrzegorzM

Reputation: 842

Look here if you realy want to do this with method syntax LINQ:

SO Multiple tables join with lambdas

Also look here:

http://msdn.microsoft.com/pl-pl/library/bb534675(v=vs.110).aspx

for Join extension method syntax. Usage presented in your code is wrong.

Upvotes: 2

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