select avanced - Mailing list pgsql-hackers

I have the following table:

Objeto        Valor

ob1        10
ob1        20
ob2        50
ob2        10
ob3        50

With the following command:

"select distinct Objeto, sum(valor) from tb
group by Objeto;"


I have to return:

Objeto        Valor

ob1        30
ob2        60
ob3        50

What you need to do is add ob2 and ob3 in one field,
Leading me the following table:


Objeto        Valor

ob1        30
ob2e3        110


It can do this only with Select?