Hi kris_tian,
I'm sorry, but I really do not understand your question.
Could you indicate the version of the plugin you are using?
Do you want store the value of a specific field in your own database?
Could you indicate the structure of your database?
If you are using the Developer version of the plugin, please visit the following link to our technical blog:
http://blog.net-factor.com/how-store-data-sent-different-database/
Best regards.