sql 语句的执行顺序

(1) from 
(3) join 
(2) on  
(4) where 
(5) group by(这里写开始使用select中的别名，后面的语句中都可以使用)
(6) avg,sum.... 
(7) having 
(8) select 
(9) distinct 
(10) order by 

写的顺序：select... from... where.... group by... having... connt(Email)>1, order by.. limit [offset,] 
(rows)
执行顺序：from... where... group by... having.... select ... order by... limit

详细过程：https://www.cnblogs.com/yyjie/p/7788428.html