sqlzoo练习答案--SELECT within SELECT Tutorial

List each country name where the population is larger than that of ‘Russia‘.

world(name, continent, area, population, gdp)

SELECT name FROM world
  WHERE population >
     (SELECT population FROM world
      WHERE name=‘Russia‘)

SELECT name FROM world
  WHERE gdp/population >
     (SELECT gdp/population FROM world
      WHERE name=‘United Kingdom‘) and continent=‘Europe‘

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

select name,population from world where population > (select population from world where name=‘Canada‘) and population <(select population from world where name=‘Poland‘) order by name

Germany (population 80 million) has the largest population of the countries in Europe. Austria (population 8.5 million) has 11% of the population of Germany.

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(100*population/(select population from world where name=‘Germany‘)),‘%‘) from world where continent=‘Europe‘

select name from world where gdp > ALL(select gdp from world where gdp > 0 and continent=‘Europe‘)

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

 select continent,name from world x where x.name=(select y.name from world y where y.continent=x.continent order by name limit 1)

SELECT name, continent, population FROM world x
  WHERE 25000000>=ALL (SELECT population FROM world y
                         WHERE x.continent=y.continent
                         AND population>0)

select name,continent from world x where x.population/3 >= all(select population from world y where x.continent=y.continent and x.name!=y.name and y.population>0)