SQL語法錯誤，我沒有看到它

Question

我的查詢中有錯誤。下面是該查詢：

select HourTime, count(*) from 
(
select substring(time,1,2) as HourTime, count(*) as ActivityCount 
from htmp_cs368 a 
group by HourTime 
)htmp 
union 
(
select substring(time,1,2) as HourTime, count(*) as ActivityCount 
from atmp_cs368 a 
group by HourTime 
)atmp 
group by HourTime DESC 

這裏是錯誤消息：

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that  corresponds to your MySQL server version for the right syntax to use near 'atmp 
group by HourTime DESC' at line 12 

任何人都可以看到它在我的錯誤是什麼？我很感激。這是alger程序的一部分，因此是java標籤。

Answer 1

GROUP BY沒有訂單。你需要排序ORDER BY。

GROUP BY HourTime 
ORDER BY HourTime DESC 

Answer 2

我想你的意思是：

... 
group by HourTime 
order by HourTime desc