Android : Update in sqlite database from another activity?

I have made a class MyDBHandler.java which contains a user defined function to update data like update mytable(String email,String table_name). I want to update the data in a table by passing email and table_name from another activity. How can I do it.

Currently I m writing this is MyActivity.java but it is not working.

MyDBHandler db;

db=new MyDBHandler(this,null,null,1);

db.update(current_email,"table");