SELECT sno,cno,score
from sc
where (cno<>'C1') AND (CNO<>'C2')
这样并不对诶
SELECT sno,cno,score
from sc
where (cno<>'C1') AND (CNO<>'C2')
这样并不对诶
SELECT sno,cno,score FROM sc WHERE (cno<>'C1') AND (CNO<>'C2') AND sno NOT IN(SELECT sno FROM sc WHERE cno in('C1','C2'));