public static boolean TRNExist(String trn){
        SQLiteJDBC db = new SQLiteJDBC();
        String sql = String.format("SELECT user_id FROM customers WHERE trn='%s'", trn);
        ResultSet resultSet = db.query(sql);
        
        try {          
            if(resultSet.next()){
                db.close();
                return true;
            }            
            db.close();
        }catch(SQLException e) {
            System.err.println( e.getClass().getName() + ": " + e.getMessage() );
            System.exit(0);
        } 
        
        return false;
    }