在同一张桌子上执行合并

由偏执旳温柔发布于 2020-05-24 01:38:14

我想在同一张桌子上执行合并以合并两个不同的结果，来自两个不同区域的top3航班但我无法执行order by子句才能获得两个选择的前3条记录，请帮助可以使用SQL中的WITH子句完成相同的查询，但在MySQL上不起作用

2020-05-24 01:38:15

You have two identical queries connected by union. Because union removes duplicates, this is equivalent to:

select count(*) as numberofflights, origin
from flights
where destination = 'EWR'
group by origin
order by numberofflights desc;

No union is necessary. Your version just adds much unneeded overhead.

这家伙很懒，什么都没留下