text: /* 1 problem */
  SELECT name, continent, population FROM world
  
  /* 2 problem */
  SELECT name
    FROM world
   WHERE population >= 200000000
  
  /* 3 problem */
  SELECT name, GDP/population
    FROM world
   WHERE population >= 200000000
  
   /* 4 problem */
  SELECT name, population/1000000
    FROM world
  WHERE continent = 'South America'
  
   /* 5 problem */
  SELECT name, population
    FROM world
  WHERE name IN ('France', 'Germany', 'Italy')
  
   /* 6 problem */
  SELECT name FROM world
  WHERE name LIKE '%United%'
  
   /* 7 problem */
  SELECT name, population, area
    FROM world
  WHERE area > 3000000 OR population > 250000000
  
   /* 8 problem */
  SELECT name, population, area
    FROM world
  WHERE area > 3000000 XOR population > 250000000
  
   /* 9 problem */
  SELECT name, ROUND(population/1000000, 2),
  ROUND(GDP/1000000000, 2)
    FROM world
  WHERE continent = 'South America'
  
   /* 10 problem */
  SELECT name, ROUND(GDP/population, -3)
    FROM world
  WHERE GDP >= 1000000000000 
  
   /* 11 problem */
  SELECT name, capital
    FROM world
   WHERE LENGTH(name) = LENGTH(capital)
  
   /* 12 problem */
   SELECT name, capital
  FROM world
  WHERE LEFT(name,1) = LEFT(capital,1) AND name <> capita
  
   /* 13 problem */
   SELECT name
     FROM world
  WHERE name LIKE '%u%' 
        and name LIKE '%a%' 
        and name LIKE '%o%' 
        and name LIKE '%i%'
        and name LIKE '%e%'
        and name NOT LIKE '% %'