DECLARE @A TABLE (a INT NOT NULL UNIQUE)
DECLARE @B TABLE (b INT NOT NULL)

SELECT COUNT_BIG(*) 
FROM @A
RIGHT LOOP JOIN @B ON
 [@B].b = [@A].a

create table parent(id int primary key)
create table child(id int primary key, parent_id int not null references parent(id))

select c.*
from dbo.child c
inner join parent p on p.id = c.parent_id