select stu.*, sco.C_name as C_name, sco.Grade as Grade
from student stu, score sco
where stu.Id = sco.Stu_id
and sco.Grade < 95 and stu.Department = '计算机';
select * from student,score where student.id = score.Stu_id and score.C_name = '计算机' and score.Grade < 95