SELECT DISTINCT F.NOME
FROM FABRICANTE F
WHERE F.CODF IN
(SELECT PF.NUMF FROM PF
WHERE PF.NUMP IN
(SELECT P.NUMP FROM PECA P
WHERE COR = 'Azul')))

SELECT DISTINCT F.NOME
FROM FABRICANTE F INNER JOIN PF INNER JOIN PECA P
ON F.CODF = PF.NUMF
AND PF.NUMP = P.NUMP
WHERE COR = 'Azul'

SELECT DISTINCT F.NOME, F.CODF, P.NUMP
FROM FABRICANTE F, PF, PECA P
WHERE F.CODF = PF.NUMF
AND PF.NUMP = P.NUMP
AND COR = 'Azul'

SELECT DISTINCT F.NOME
FROM FABRICANTE F
WHERE (SELECT PF.NUMF FROM PF
WHERE (SELECT P.NUMP FROM PECA P
WHERE COR = 'Azul')))

SELECT DISTINCT P.NUMP
FROM FABRICANTE F, PF, PECA P
WHERE PF.NUMP = P.NUMP
AND F.CODF = PF.NUMF
AND COR = 'Azul'