常见查询语句：

select  ....  from .... where  .. group by ... having ... order by .. limit...

　　输出　 获取数据     过滤  　　分组　　　 过滤       排序　  限定个数 

 

以上为书写顺序，以下为执行顺序：

from  ->  where -> group by - >select - > having -> order by -> limit