Question

Registered table has stucture

regid
userid

var Registered = form r in dc.registered  where ... // list contains userid as f.k.

I want user list who has registered.

so query like

var user = from u in dc.users where u.userid in // should contains in Register.userid

I want to learn more about linq where I can find best stuffs?

Answer 1

I suspect you want:

var users = from u in dc.users 
            join r in Registered on u.userid equals r.userid
            select u;

Note that this will be more efficient than an “Any” solution as it will build up the set of registered user IDs once (as a hashset) at which point the test for each user is quick.