SELECT *
FROM SC
LEFT JOIN S ON SC.S = S.S
LEFT JOIN C ON SC.C = C.C
WHERE SC.GRADE >= 60 AND S.SEX = '女'
SELECT DISTINCT S.NAME
FROM SC
LEFT JOIN S ON SC.S = S.S
WHERE SC.GRADE >= 60 AND S.SEX = '女'
FROM SC
LEFT JOIN S ON SC.S = S.S
LEFT JOIN C ON SC.C = C.C
WHERE SC.GRADE >= 60 AND S.SEX = '女'
SELECT DISTINCT S.NAME
FROM SC
LEFT JOIN S ON SC.S = S.S
WHERE SC.GRADE >= 60 AND S.SEX = '女'
select s.s,s.name,c.format,sc.grade
from s, c left join sc
on s.s=sc.s and c.c=sc.c
where sc.grade >= 60
group by s.s order by sc.grade;select s.s,s.name,c.format,sc.grade
from s, c left join sc
on s.s=sc.s and c.c=sc.c
where sc.grade >= 60 and s.sex='f'
group by s.s order by sc.grade;其中group by后面可以跟c.format来分组而不用s.s。希望楼主试过之后能够及时反馈,谢谢!