How to create Davies Bouldin Index for algoritm DBSCAN ?

Hello...

I have a problem, i want to try different algorithms K-Means and DBSCAN on my dataset and compare the result to find Davies Bouldin Index best validation cluster. 
i can already to make K-means with result DBI but, i can't make modeling design for DBSCAN to find DBI (Davies Bouldin Index).
anyone know to create modeling design to find Davies Bouldin Index for Algorithm DBSCAN ?


thanks for your help.