在Hive中查询时获取NaN值

Question

我在Hive中解雇了以下查询： -

SELECT gender_hh_mem1, (sum(if(CLICK_FLG='Y' and OPEN_FLG='Y', 1, 0))/
 sum(if(OPEN_FLG='Y', 1, 0))*100) as CTOR FROM campaigndata 
WHERE gender_hh_mem1 is not null 
GROUP BY gender_hh_mem1;

我得到以下结果： -

F       11.827956989247312<br>
M       15.18987341772152<br>
U       18.181818181818183<br>
gender_hh_mem1  <b>NaN</b>

为什么我在这里NaN？任何线索？