以下代码未经测试, 这个题目是 《数据库系统概论(第四版)》关系运算中除法 中的例题,select * from stu s where not exists (select 1 from stu_kecheng where stu_id=s.id and kecheng_id not in (select kecheng_id from stu_kecheng where stu_id=(select id from stu where name='张三'))) and not exists (select 1 from stu_kecheng where stu_id=(select id from stu where name='张三') and kecheng_id not in (select kecheng_id from stu_kecheng where stu_id=s.id))
from stu s
where not exists (select 1 from stu_kecheng where stu_id=s.id and kecheng_id not in (select kecheng_id from stu_kecheng where stu_id=(select id from stu where name='张三')))
and not exists (select 1 from stu_kecheng where stu_id=(select id from stu where name='张三') and kecheng_id not in (select kecheng_id from stu_kecheng where stu_id=s.id))