You can use a QueryRecord processor before the PutDatabaseRecord.

You can add a relation to the QueryRecord processor with the following associated query:

select
"field one" as field_one,
"field two" as field_two,
"field three" as field_three
from flowfile

 In the query above you can reference one field names using double-quotes if they have spaces. You can specify an alias for that column, which is the field name that will be used in the output.

Cheers,

Andre