Question

Hey I don’t know how to do it….

Its a homework: List the code and the consumers who bought cars only ‘Argentina’ country.

Table sell:

customer | resell  | veicle    |    date    |  value
---------+---------+-----------+------------+----------
 02      | 01      | 03        | 2010-02-05 | 17500.00
 04      | 02      | 01        | 2010-01-07 | 28000.00
 01      | 03      | 08        | 2010-02-15 | 28000.00
 02      | 03      | 02        | 2010-03-12 | 42000.00
 03      | 04      | 06        | 2010-02-06 | 11500.00
 03      | 02      | 05        | 2010-01-25 | 22100.00
 01      | 01      | 04        | 2010-01-21 | 15500.00

Table customer:

 cod    |    name    | lastname
--------+------------+------------
 01     | Jose       | Alves
 02     | Paulo      | Cunha
 03     | Maria      | DPaula
 04     | Joana      | Silveria

Table veicle:

 cod    |manufacturer|     model       | year |  country  |  price
--------+------------+-----------------+------+-----------+----------
 01     | 01         | Gol             | 2000 | Brasil    | 25000.00
 02     | 01         | Golf            | 2005 | Argentina | 39000.00
 03     | 04         | Ford Ka         | 1990 | Brasil    | 15000.00
 04     | 03         | Corsa Seda      | 1995 | Brasil    | 12500.00
 05     | 04         | Fiesta          | 2003 | Argentina | 20000.00
 06     | 03         | Corsa Seda      | 1995 | Argentina | 10000.00
 07     | 05         | Palio           | 2002 | Brasil    | 15000.00
 08     | 05         | Siena           | 2006 | Brasil    | 26000.00

I guess it to start:

SELECT customer.cod, customer.name 
FROM sell, customer 
WHERE (SELECT cod 
        FROM veicle 
        WHERE veicle.country = 'Argentina') = sell.veicle;

To select only the argentine cars…
Please guide-me to the answer.

Answer 1

SELECT c.*
FROM   customer c
WHERE EXISTS (
    SELECT 1
    FROM   sell s
    JOIN   veicle v ON v.cod = s.veicle
    WHERE  s.customer = c.cod
    AND    v.country = 'Argentina'
    )
AND NOT EXISTS (
    SELECT 1
    FROM ...
    );

I’ll leave the rest for you, as this is homework. Fill in for ... to exclude customers that have bought vehicles that are not from Argentina – very similar to the first EXISTS clause. If you have understood the first, you can complete the rest.