Query in postgreSQL version Windows

Hello, there
I installed PostgreSQL on windows and when I try to run some query's pgadmin says an error. I know that if I change the query this it will work but is it possible to make this quey work in this way

SELECT atthasdef
FROM pg_attribute
WHERE attrelid=pg_class.oid AND pg_class.relname='client_overtime' AND attname='id_client_overtime'

Thx