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或者这样写:
SELECT STUDENT.SNAME
FROM STUDENT
WHERE NOT EXISTS (SELECT *
FROM COURSE
WHERE NOT EXISTS (SELECT *
FROM S_C
WHERE SNO = STUDENT.SNO
AND CNO = COURSE.CNO));
应该这么写:
SELECT SNAME
FROM STUDENT
WHERE SNO IN (SELECT SNO
FROM (SELECT SNO, COUNT(1) CC FROM S_C GROUP BY SNO)
WHERE CC = (SELECT COUNT(*) FROM COURSE))
[Quote=引用楼主 hwfwh007 的帖子:]