Issue in upgrading database when new version of application created

I am created application and uploaded to Google Play Store. Now i make changes in that, added new functionality because of that my database is changes, new column in table and new table has been added. I use singleton object to handle database. Now I change database version to call onUpgrade(); to DROP allready existing table and then call onCreate(); to create table again. But i am not getting proper result as expected. Please share if anyone have code to upGrade table successfully in onUpgrade(). Thank you.