多表 测试

select*
from Class join Student
on Class .ClassNo =Student .ClassNo
join StuCou
on Student .StuNo =StuCou .StuNo
join Course
on StuCou .CouNo =Course .CouNo
join achievement
on StuCou .StuNo =achievement .StuNO
where Class .ClassName ='2015（3+2）计算机'