T-Sql exists Usage:

select *
from Customers c
where exists(select *
from Orders
where ShipCountry = ‘Germany’
and CustomerId = c.CustomerId)

Linq contains usage instead of exists:

DataClassesDataContext db = new DataClassesDataContext();
var Cust = from c in db.Customers
where (from o in db.Orders
where o.ShipCountry == “Germany”
select o.CustomerID).Contains(c.CustomerID)
select c;