【正确答案】① SELECT *
FROM SPJ
WHERE QTY BETWEEN 300 AND 500
② SELECT Jname
FROM J
WHERE Jno IN(SELECT Jno
FROM SPJ
WHERE Sno IN(SELECT Sno
FROM SPJ
WHERE Pno IN(SELECT Pno
FROM P
WHERE Color='红')))
③ SELECT Jname FROM J
WHERE NOT EXISTS(SELECT *
FROM SPJ SPJX
WHERE Sno='S1' AND NOT EXISTS
(SELECT *
FROM SPJ SPJY
WHERE SPJX.Pno=SPJY.Pno
AND SPJY.Jno=J.Jno));