Switching to Realm, how to execute such a request?

Question

Android

I'm moving the project to realm, how can I query multiple tables in it?
There was a request like this:

public Integer getPrescriptionsCount(Date from, Date to) {
        List<PrescriptionItem> items = new ArrayList<>();
        SQLiteDatabase db = this.getWritableDatabase();
        try {
            String selectQuery = "SELECT  * FROM " + TABLE_PRESCRIPTIONS + "," + TABLE_EXEC_TEMPLATE
                    + " WHERE " + TABLE_PRESCRIPTIONS + "." + KEY_PRESCRIPTIONS_START_DATE + " <= '" + dateFormatWOutTime.format(from) + " 00:00:00' AND ("
                    + TABLE_PRESCRIPTIONS + "." + KEY_PRESCRIPTIONS_END_DATE + " >= '" + dateFormatWOutTime.format(to) + " 99:99:99'"
                    + " OR " + TABLE_PRESCRIPTIONS + "." + KEY_PRESCRIPTIONS_END_DATE + " IS NULL)"
                    + " AND " + TABLE_EXEC_TEMPLATE + "." + KEY_EXEC_TEMPLATE_PRESCRIPTION_ID + " = " + TABLE_PRESCRIPTIONS + "." + KEY_ID
                    + " ORDER BY " + TABLE_EXEC_TEMPLATE + "." + KEY_EXEC_TEMPLATE_DISPLAY_ORDER;

            Log.e(LOG, selectQuery);
            Cursor c = db.rawQuery(selectQuery, null);
            return c.getCount();
        } finally {
            db.close();
        }
    }

how to transfer it to realm?
ps yes, you can't say that the request is adequate, but what web service -> such and database -> such and request (sad)
pps Thanks in advance!