4-SELECT-within-SELECT.md

Questions Index

• Ques 1

• Ques 2

• Ques 3

• Ques 4

• Ques 5

• Ques 6

• Ques 7

• Ques 8

• Ques 9

• Ques 10

Ques 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'
		)

Ques 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'
		)

Ques 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

Ques 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 IN ('Canada')
		)
	AND population < (
		SELECT population
		FROM world
		WHERE name IN ('Poland')
		)

Ques 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
				))
		,'%'
		)
FROM world
WHERE continent = 'Europe'

Ques6. Which countries have a GDP greater than every country in Europe?

SELECT name
FROM world
WHERE gdp > (SELECT max(gdp) FROM world WHERE continent  = 'Europe')

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

SELECT continent, name, area
FROM world
WHERE area IN (SELECT max(area) FROM world GROUP BY continent)

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

SELECT continent, MIN(name) as name
FROM world
GROUP BY continent
ORDER BY continent

Ques 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
WHERE continent NOT IN (
	SELECT continent
	FROM world
	WHERE population > 25000000
)

Ques 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 x.name, continent
FROM world x
WHERE x.population / 3 > ALL (
	SELECT y.population
	FROM world y
	WHERE x.continent=y.continent AND x.name != y.name
)