text: /* 21. Страни и валута  (Euro / Not Euro) */
  USE geography;
  
  SELECT country_name, country_code, 
  
  /* Пример 1 */
  CASE WHEN currency_code = "EUR" THEN "EURO" ELSE "NOT EURO" END as currency1,
  /* Пример 2 */
  IF(currency_code="EUR","EURO","NOTEURO") as currency2
  
  FROM countries
  ORDER BY country_name;
  