4 SELECT within SELECT

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
      DISTINCT(continent)
    FROM
      world
    WHERE
      name = 'Argentina'
      OR name = 'Australia'
  )
ORDER BY
  name

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(100*population/(SELECT population FROM world WHERE name = 'Germany')), '%')
FROM
  world
WHERE
  continent = 'Europe'

6.

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

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

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

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
  3 * population
FROM
  world y
WHERE
  x.continent = y.continent
  AND x.name != y.name
)