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

这是错误消息:

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

任何人都可以看到我的错误在哪里？我很感激.这是一个较大程序的一部分,因此是java标记.

Answer 1

GROUP BY没有订单.你需要排序ORDER BY.

GROUP BY HourTime 
ORDER BY HourTime DESC