//新增
$rs = DB::insert('insert into student(name,age) values (?,?)',['kit',20]);
//更新
$rs = DB::update('update student set age=? where name=?',[20,'Doubly']);
//删除
$rs = DB::delete('delete from student where name=?',['kit']);
//查询
$rs = DB::select('select * from student');