我有一个数据列，其列为“ CUSTOMER_MAILID”，“ OFFER_NAME”，“ OFFER_ISAPPLIED”。
样本数据：
+--------------------+--------------------+---------------+
| CUSTOMER_MAILID| OFFER_NAME|OFFER_ISAPPLIED|
+--------------------+--------------------+---------------+
|pushpendrakaushik...|Jaipur Pink Panth...| N|
|pushpendrakaushik...|Jaipur Pink Panth...| N|
|dr.kshitijmathur@...| | N|
|spdadhichassociat...| | N|
|vinod.gogia@herom...|Jaipur Pink Panth...| N|
|prerak0401@gmail.com| | N|
| garhwalsp@gmail.com| | N|
|muditsharma1985@g...| | N|
| amit1185@gmail.com|Jaipur Pink Panth...| N|
如果“ OFFER_NAME”列具有某些值（空值除外），我想用“ Y”更新“ OFFER_ISAPPLIED”列值。
我该如何实现？
输出应如下所示：
+--------------------+--------------------+---------------+
| CUSTOMER_MAILID| OFFER_NAME|OFFER_ISAPPLIED|
+--------------------+--------------------+---------------+
|pushpendrakaushik...|Jaipur Pink Panth...| Y|
|pushpendrakaushik...|Jaipur Pink Panth...| Y|
|dr.kshitijmathur@...| | N|
|spdadhichassociat...| | N|
|vinod.gogia@herom...|Jaipur Pink Panth...| Y|
|prerak0401@gmail.com| | N|
| garhwalsp@gmail.com| | N|
|muditsharma1985@g...| …