sql - Return a default value when a match found -

i return records (entryids) , language flag selected, want return yes instead of actual value in attributevalue field. i've tried returns actual value populated rathern yes match found. think need exists returns many rows each language associated entryids.

select distinct x.entryid, isnotnull(a.attributevalue, 'yes') entry x left outer join entryattribute e on e.entryid = x.entryid left outer join attributestring on a.attributeid = e.attributeid  a.attributedefinitionid = 44  

use case statement. example:

case when attributevalue not null 'yes' else 'no' end