MySQL_CRUD基础语句
================增========================= insert into ______ value ______ , ______; 自我复制 insert into users (username,password,email,grade) select username,password,email,grade from users ================删========================= delete from _____ where _____; ================改========================= update ______ set ______; ================查========================= 升降排序：select ____ from ____ order by id (asc|desc); 模糊查询：select ___ from ____ where col-name like '(%|_)'; 分页查询：select ___ from ____ where ____ limit m,n; 分组查询：select ___ from ____ where ____ group by ____ having___; 多表查询：