text: -- 1. Show the name, continent and population of all countries.
  SELECT name, continent, population
    FROM world
  
  -- 2. Show the name for the countries that have a population of at least 200 million. 200 million is 200000000.
  SELECT name
    FROM world
   WHERE population > 200000000
  
  -- 3. Give the name and the per capita GDP for those countries with a population of at least 200 million (per capita GDP is the GDP divided by the population GDP/population)
  SELECT name, GDP/population
    FROM world
   WHERE population > 200000000
  
  -- 4. Show the name and population in millions for the countries of the continent 'South America'. Divide the population by 1000000 to get population in millions.
  SELECT name, population/1000000
    FROM world
   WHERE continent = 'South America'
  
  -- 5. Show the name and population for France, Germany, Italy
  SELECT name, population
    FROM world
   WHERE name IN ('France', 'Germany', 'Italy')
  
  -- 6. Show the countries which have a name that includes the word 'United'
  SELECT name
    FROM world
   WHERE name LIKE 'United%'
  
  -- 7. Show the countries that are big by area or big by population. Show name, population and area.
  SELECT name, population, area
    FROM world
   WHERE area > 3000000 OR population > 250000000
  
  -- 8. Show the countries that are big by area (more than 3 million) or big by population (more than 250 million) but not both. Show name, population and area.
  SELECT name, population, area
    FROM world 
   WHERE area > 3000000 XOR population > 250000000
  
  -- 9. Show the name and population in millions and the GDP in billions for the countries of the continent 'South America'. Use the ROUND function to show the values to two decimal places.
  SELECT name, ROUND(population/1000000, 2), ROUND(GDP/1000000000, 2)
    FROM world
   WHERE continent = 'South America'
  
  -- 10. Show the name and per-capita GDP for those countries with a GDP of at least one trillion (1000000000000; that is 12 zeros). Round this value to the nearest 1000.
  SELECT name, ROUND(gdp/population, -3)
    FROM world 
   WHERE gdp >= 1000000000000
  
  -- 11. Show the name and capital where the name and the capital have the same number of characters.
  SELECT name, capital 
    FROM world
   WHERE LENGTH(name) = LENGTH(capital)
  
   -- 12. Show the name and the capital where the first letters of each match. Don't include countries where the name and the capital are the same word
  SELECT name, capital
    FROM world
   WHERE LEFT(name, 1) = LEFT(capital, 1) XOR name = capital
  
   -- 13. Find the country that has all the vowels and no spaces in its name.
   SELECT name
    FROM world
   WHERE name LIKE '%a%'
    AND name LIKE '%e%'
    AND name LIKE '%i%'
    AND name LIKE '%o%'
    AND name LIKE '%u%'
    AND name NOT LIKE '% %'