Duplicate file check at DB table

Hi Friends,

My scenario is File to JDBC and while insert the file first time to DB, i am fectching the file name dynamically and inserting to DB table.

now my requirement is when i process the files to DB, it should check whether the file was lareday processed or not. So how can i do this in PI70.

i found that we can do that by using UDF in Mapping. if so please provide me the lookup code(Java) to check the file name from DB.

i craeted a look up channel and db table with the field "PI_filename". So please help me with UDF-Java code

Best Regards,SARAN