编写顺序:
select → form → where → group by → having → order by → limit
执行顺序:
from → on → join → where → group by → 聚合函数 →with rollup → having → select → distinct → order by → limit
编写顺序:
select → form → where → group by → having → order by → limit
执行顺序:
from → on → join → where → group by → 聚合函数 →with rollup → having → select → distinct → order by → limit