[sqlzoo] SELECT from WORLD Tutorial 정답, 풀이

-- 1.Introduction
SELECT name, continent, population FROM world

-- 2.Large Countries
SELECT name FROM world
WHERE population >= 200000000

-- 3.Per capita GDP (1인당 국내 총생산)
SELECT name, GDP/population
FROM world
WHERE population >= 200000000

-- 4.South America In millions
SELECT name, population/1000000
FROM world
WHERE continent='South America'

-- 5.France, Germany, Italy
SELECT name, population
FROM world
WHERE name IN ('France', 'Germany', 'Italy')

-- 6.United
SELECT name
FROM world
WHERE name LIKE '%United%'

-- 7.Two ways to be big
SELECT name, population, area
FROM world
WHERE area >= 3000000 OR population >=250000000

-- 8.One or the other (but not both)
SELECT name, population, area
FROM world
WHERE (area > 3000000 AND population<250000000) OR (area < 3000000 AND population>250000000) 

-- 9.Rounding
SELECT name, ROUND(population/1000000,2), ROUND(gdp/1000000000,2)
FROM world
WHERE continent='South America'

-- 10.Trillion dollar economies
SELECT name, ROUND(gdp/population, -3)
FROM world
WHERE gdp>1000000000000

-- 11.Name and capital have the same length
-- Correct 확인 안됨..
SELECT name, capital 
FROM world 
WHERE LEN(name) = LEN(capital);

-- 12.Matching name and capital
-- <> as the NOT EQUALS
SELECT name, capital
FROM world
WHERE LEFT(name,1)= LEFT(capital,1)
	AND name<>capital

-- 13.All the vowels
SELECT name
  FROM world
WHERE name LIKE '%a%'
  AND name LIKE '%e%'
  AND name LIKE '%i%'
  AND name LIKE '%o%'
  AND name LIKE '%u%'
  AND name NOT LIKE '% %'