4 SELECT within SELECT Tutorial

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1. List each country name where the population is larger than that of 'Russia’

SELECT name FROM world
  WHERE population >
     (SELECT population FROM world
      WHERE name='Russia');

2. Show the countries in Europe with a per capita GDP greater than 'United Kingdom’

select name from world
where continent =  'Europe'
and gdp/population >
(select gdp/population from world
where name = 'United Kingdom');

3. List the name and continent of countries in the continents containing either Argentina or Australia. Order by name of the country

select name,continent from world
where continent in
(select continent from world
where name in ('Argentina','Australia'))
order by name;

4. Which country has a population that is more than Canada but less than Poland? Show the name and the population

select name,population from world
where population >
(select population from world
where name = 'Canada')
and population <
(select population from world
where name = 'Poland');

5. Show the name and the population of each country in Europe. Show the population as a percentage of the population of Germany

select name,
concat(round((population / 
(select population from world where name = 'Germany'))*100,0),'%')
from world
where continent = 'Europe';

6. Which countries have a GDP greater than every country in Europe? [Give the name only.] (Some countries may have NULL gdp values)

SELECT name FROM world
WHERE gdp > ALL
(SELECT gdp FROM world 
WHERE continent = 'Europe' and gdp>0);

7. Find the largest country (by area) in each continent, show the continent, the name and the area:

SELECT continent, name, area FROM world x
  WHERE area >= ALL
    (SELECT area FROM world y
        WHERE y.continent=x.continent
          AND area>0);

8. List each continent and the name of the country that comes first alphabetically

select continent,min(name) from world
group by continent;

9. Find the continents where all countries have a population <= 25000000. Then find the names of the countries associated with these continents. Show name, continent and population

select name, continent, population from world x
where 25000000 >= all
(select population from world y
where x.continent = y.continent
and population >0);

10. Some countries have populations more than three times that of any of their neighbours (in the same continent). Give the countries and continents

select name,continent from world x
where x.population > all
(select 3*population from world y
where x.continent = y.continent
and y.population >0
and x.name <> y.name);

4 SELECT within SELECT Tutorial

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