This little snippet returns your expected output:

declare @t table

(

id char(2),

type int

)

insert @t (id, type) values

('c1', 0)

,('c2', 5)

,('c3', 0)

,('c4', 0)

,('c4', 7)

,('c5', 9)

,('c6', 4)

,('c6', 0)

,('c7', 7)

,('c8', 0)

,('c9', 0)

select t.id, SUM(type) from @t t

group by id

having count(*) = 1 and SUM(type) = 0