介绍一下Order by 的几种用法

1. 按列名排序，默认是升序的。
单列升序：select from order by ;
单列降序：select from table_name order by desc;
多列升序：select , from table_name order by , ;
多列降序：select , from order by desc, desc;
多列混合降序：select column_one, column_two from table_name order by column_one desc, column_two desc;