I just finished making my first android app. Currently the database helper contains this method:

```
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS "+SUBJECTS_TABLE_NAME);
    onCreate(db);
}

```

After some googling I'm getting contradictory information about what exactly I should put in this method. When I update the app I don't want to change the database, and I think this method will currently erase user data? What is the best way to run an update that doesn't change any of the database?