help query

hi everyone,

i've got this oracle query, and i need it to put it to work in potgresql
platform, i think the right outer join it will do just fine, but i don't
now where to put , can anyone help me:

select id_mensagem, ds_description, e_mail,
to_char(date,'DD/MM/YY - HH24:MI') as Date, assunto, respondidas,
mensagem, mensagens.id_resposta
from (select id_mensagem, ds_description, e_mail, date, assunto,
mensagem, id_resposta
from tb_mensagens_monitores
where tb_mensagens_monitores.id_resposta is null) mensagens,
(select id_resposta, count(id_mensagem) as respondidas
from tb_mensagens_monitores group by id_resposta) as respostas
where mensagens.id_mensagem = respostas.id_resposta(+)
order by date

kind regards,

rute