查询两门及其以上不及格课程的同学的,姓名及其平均成绩select student.SId, student.Sname, t2.avgscorefrom student, (select sc.SId, avg(sc.score) as avgscore from sc group by sc.SId) as t2where student.SId = t2.SIdand student.SId in (select t1.SId from(select * from scwhere sc.score < 60) as t1group by t1.SIdhaving count(*) >= 2)