将班级号(class_id)为g99402的全体学生的笔试成绩加10分。（分别用相关子查询和不相关子查询完成）

使用相关子查询：

UPDATE student SET exam_score = exam_score + 10 WHERE class_id = 'g99402';

使用不相关子查询：

UPDATE student SET exam_score = exam_score + 10 WHERE student_id IN (SELECT student_id FROM student WHERE class_id = 'g99402');