Hi Swetha ,
If you dont have access to the file you need to handle in the job design .
1. Take key field or some non blank fields.
2. Use the decode function in the where length(field) <> 0
or
3. use any extra query with extra field with name flag.
4. flag mapping with me like decode(length(field)<>0 or field is not null,'non blank' ,'blank')
5. Use flag <> 'blank' in the where clause.
I hope your data set might contain at least one field with whole data else combination of few fields.
Thanks &Regards,
Ramana.