HiveQL stdev和按问题分组

Question

想知道Hive QL Stdev_pop - 此查询有效

Error
SQL query:
UPDATE Estimates
SET CreatedDate = str_to_date( CreatedDate, '%c/%e/%y' )
MySQL said: #1411 - Incorrect datetime value: '' for function str_to_date

但是，std偏差（应与上面相同）给出错误，如;

$sql =  "SELECT * FROM postImg RIGHT JOIN user ON postImg.userID=user.userID 
    WHERE user.userID='".$page_owner."' AND (userName LIKE '%".$searchVal."%') GROUP BY user.userID ";

我也尝试了stdev_sample并出现了同样的错误。

有人知道为什么蜂巢会逐渐期待？