Expense header level DFF - default value with SQL type

I would like to create DFF with sql type default value to populate person name/employee name who is raising expense report.

Don’t see any bind parameters available for DFF flex code “EXM_EXPENSE_REPORT_HEADER” with below sql

select * from FND_DF_PARAMETERS

where DESCRIPTIVE_FLEXFIELD_CODE  like 'EXM_EXPENSE_REPORT_HEADER'.

Let me know is there a way to default DFF with person name/employee name who is raising expense report.

Thanks,

Manjunath.