Problem in SQL selection

Question

Why even if I filter to return only the fiat manufacturer, keeps returning other values?

 SELECT FABRICANTE, MODELO, VALOR_DIARIA FROM VEICULO 
    WHERE VALOR_DIARIA = (SELECT MIN(VALOR_DIARIA) FROM VEICULO WHERE FABRICANTE = 'FIAT')

Upshot:

FABRICANTE                     MODELO                         VALOR_DIARIA
------------------------------ ------------------------------ ------------
VOLKSWAGEN                     GOL                                      80
FIAT                           PALIO                                    80

Answer 1

The problem is that you used a sub-volume to filter the values, which is not necessary. In this case, the value of FIAT’s daily rate is equal to that of VOLKSWAGEN and, as the sub-volume returns "80", it brings both. The correct would simply be:

SELECT FABRICANTE, MODELO, VALOR_DIARIA FROM VEICULO WHERE FABRICANTE = 'FIAT';

Ideally, you should use a filter that uses fields that are primary keys and avoid filtering directly into text to find exact values. Either way this is gonna work.

In case you need to choose the lowest value, you can add one more criterion, type like this:

SELECT FABRICANTE, MODELO, VALOR_DIARIA FROM VEICULO WHERE FABRICANTE = 'FIAT' AND VALOR_DIARIA = (SELECT MIN(VALOR_DIARIA) FROM VEICULO WHERE FABRICANTE = 'FIAT');

Or any other criteria prioritizing the record you need.

It can be done also the limitation of lines, forcing the bank to bring the first line. Type so:

SELECT FABRICANTE, MODELO, VALOR_DIARIA FROM VEICULO WHERE FABRICANTE = 'FIAT' AND VALOR_DIARIA = (SELECT MIN(VALOR_DIARIA) FROM VEICULO WHERE FABRICANTE = 'FIAT') LIMIT 1  

Hug!