getting null when calculating time diff with unix_timestamp + spark 1.6

[Divya Gehlot]

Hi,

val lags=sqlContext.sql("select *,(unix_timestamp(time1,'$timeFmt') -
lag(unix_timestamp(time2,'$timeFmt'))) as time_diff  from df_table");

Instead of time difference in seconds I am gettng null .

Would reay appreciate the help.


Thanks,
Divya