Обсуждение: 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

(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".


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I've sent this onto the mailng lists...


On Mon, 11 Jan 1999, Jixue Jerry Liu wrote:

> Dear Marc,
>
> My name is Jixue Liu, a PhD student in the School of Computer Science,
> University of South Australia. I am studying view maintenance in OR
> Systems. The model I study most and the system I use is Postgres. I
> appreciate the contribution of Postgres group to the field. Now I have
> some questions about the usage of the system.
>
> 1. How to define a relation with an attribute which takes set values?
> 2. How to populate instances to a table referring another table? An
> example:
>    Create table cities (name text, population float);
>    Insert into cities values ('Adelaide',100.0);
>    Create table people(name text, live_in cities);
>    How to insert a tuple into people saying that 'Jerry' lives in
> Adelaide?
>
>
> I am looking forward to hearing from you.
>
> Jixue Liu
>
>
>
>

Marc G. Fournier
Systems Administrator @ hub.org
primary: scrappy@hub.org           secondary: scrappy@{freebsd|postgresql}.org