questions

2 questions.

1)Hi, I have this 2 tables:
esame=> select * from libro_autore\g
id_libro|id_autore
--------+---------
s1 | 5
n3 | 1
n2 | 2
n1 | 1
n1 | 4

and
esame=> select * from autore\g
cognome|nome |data_nascita|luogo_nascita|id_autore
-------+----------+------------+-------------+---------
King |Stephen | 01-12-1940|NY | 1
Tamaro |Susanna | 15-02-1965|Milano | 2
Clancy |Tom | 05-05-1968|Los Angeles | 3
Straub |Peter | 01-01-1950|Milano | 4
Maraini|Dacia | 05-04-1962|Catania | 5
Zorza |Alessandra| 05-05-1974|Cernusco | 6

Now I want to found Cognome, Nome and number of books foreach
"id_autore"
in
the libro_autore table.
I have think a SQL-statement like

SELECT a.cognome, a.nome,la.id_autore, count(*) from libro_autore la,
autore a group by l
a.id_autore\g

I don't completely understand you question but this could be what you
are looking for.
SELECT a.cognome, a.nome, la.id_autore, count(la.id_libro)
FROM libro_autore la, autore a
WHERE la.id_autore = a.id_autore
GROUP BY a.cognome, a.nome, la.id_autore;

(ok this is not correct).
Any ideas ??

2)Now I have this table:
esame=> select * from view1\g
id_libro|id_utente|tipo
--------+---------+----
n3 | 9| 1
(1 row)

(for the moment only 1 item, but this table can contains more and more
items).
I want to find a way that return me for each "id_utente" the number of
books group by
"tipo".

SELECT id_utente, tipo, count(id_libro)
FROM view1
ORDER BY id_utente, tipo
GROUP BY id_utente, tipo;