小编c_s*_*arp的帖子

我正在使用正则表达式来确定命令行参数具有.dat扩展名.我正在尝试以下正则表达式:

#define to_find "^.*\.(dat)?"

出于某种原因,我收到了我在这个问题标题中所说的警告.首先,这个表达是否正确？我相信它是.第二,如果它是正确的,我怎么能摆脱这个警告？

我在Xcode编写ac程序,上面的#define在我的.h文件中.谢谢!

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.