4 SELECT within SELECT.sql

--URL: http://sqlzoo.net/wiki/SELECT_within_SELECT_Tutorial
--1
SELECT name FROM world
  WHERE population >
     (SELECT population FROM world
      WHERE name='Russia')
      
--2
SELECT name FROM world
WHERE continent='Europe' AND gdp/population >
 (SELECT gdp/population FROM world
 WHERE name='United Kingdom')
 
 --3
 SELECT name, continent FROM world
WHERE continent IN (
SELECT continent FROM world
WHERE name='Argentina' OR name='Australia'
)
ORDER BY name ASC;

--4
SELECT name, population FROM world
WHERE population > (
SELECT population FROM world
WHERE name='Canada'
) AND population< (
SELECT population FROM world
WHERE name='Poland'
)

--5
SELECT name, CONCAT(ROUND(population/(SELECT population FROM world WHERE name='Germany')*100, 0),'%')
FROM world
WHERE continent='Europe' 

--6
SELECT name 
FROM world
WHERE gdp > ALL(SELECT gdp 
                 FROM world
                 WHERE continent='Europe'
                 AND gdp IS NOT NULL);
                 
--7
SELECT continent, name, area FROM world x
  WHERE area >= ALL
    (SELECT area FROM world y
        WHERE y.continent=x.continent
          AND area>0)
          
--8
SELECT continent, name FROM world x 
WHERE name <= ALL
      (SELECT name FROM world y
       WHERE x.continent=y.continent
       AND name IS NOT NULL);
       
--9
SELECT name, continent, population FROM world x
WHERE 25000000 >= ALL(SELECT population FROM world y WHERE x.continent=y.continent) 

--10
SELECT name, continent
FROM world x
WHERE population > ALL(
      SELECT population*3 FROM world y 
      WHERE y.continent=x.continent
      AND y.name!=x.name)