-- 9、查询学过编号为“01“并且也学过编号为“02“的课程的同学的信息

SELECT st.* FROM student st INNER JOIN score sc ON sc.s_id=st.s_id AND sc.c_id='01' WHERE st.s_id IN ( SELECT st2.s_id FROM student st2 INNER JOIN score sc2 ON sc2.s_id=st2.s_id AND sc2.c_id='02' )