public Connection getSQLConnection() {
        try {
            if (sql_connection == null || sql_connection.isClosed()) {
                Class.forName("com.mysql.jdbc.Driver");
                String url = "jdbc:mysql://" + sql.get(0) + ":" + sql.get(1) + "/" + sql.get(2);
                sql_connection = DriverManager.getConnection(url, sql.get(3), sql.get(4));
            }
        } catch (ClassNotFoundException | SQLException e) {
            this.getLogger().log(Level.SEVERE, null, e);
        }

        return sql_connection;
    }