Jdbc input doesn't manage with a date field

I'm trying to work with the JDBC plugin so it will only read recently modified events from an Oracle database. this is the configuration I have:

input {
jdbc {
jdbc_driver_library => "ojdbc7.jar"
jdbc_driver_class => "Java::oracle.jdbc.driver.OracleDriver"
jdbc_connection_string => "*"
jdbc_user => "
jdbc_password => "
#schedule => "
* * * *"
statement => "SELECT * FROM BUG WHERE bg_vts > :sql_last_start"
record_last_run => true

When I run it, I get an error saying "not a valid month".
The column bg_vts in the database has the format YYYY-MM-dd HH:mm:ss and is not mapped automatically as a date type field (unlike other formats in the database).

  1. what might be the problem?
  2. is there a way to solve it in the input?
  3. is there a way maybe to do the date filtering in the output? (using the last_start paramater and the bg_vts after a date filter)

thank you bery much!