SQL语法错误，我没有看到它

Question

我的查询中有错误。这是查询：

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

以下是错误消息：

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

有人能看到我的错误吗？我很感激。这是一个较大的程序的一部分，因此是java标记。

Answer 1

GROUP BY没有订单。您需要使用ORDER BY进行排序。

GROUP BY HourTime 
ORDER BY HourTime DESC

Answer 2

我认为你的意思是：

...
group by HourTime
order by HourTime desc