classTable:id,name;
studentTable:id,name;
class_studentTable:class_id,student_id;
变态一点的例子,想删除名称包含"2b"班级中的所有学生
delete s from studentTable as s
left outer join class_studentTable on student_id = s.id
left outer join classTable on class_id = classTable.id
where classTable.name like "%2b%"