SUM-and-COUNT.sql

--#1
--Show the total population of the world. 

SELECT SUM(population)
FROM world

--#2
--List all the continents - just once each. 

SELECT DISTINCT(continent) FROM world

--#3
--Give the total GDP of Africa 

SELECT SUM(gdp) FROM world WHERE continent = 'Africa'

--#4
--How many countries have an area of at least 1000000 

SELECT COUNT(name) FROM world WHERE area >= 1000000

--#5
--What is the total population of ('Estonia', 'Latvia', 'Lithuania') 

SELECT SUM(population) FROM world WHERE name IN ('Estonia', 'Latvia', 'Lithuania')

--#6
--For each continent show the continent and number of countries. 

SELECT continent, COUNT(name) FROM world
GROUP BY continent

--#7
--For each continent show the continent and number of countries with populations of at least 10 million. 

SELECT continent, COUNT(name) FROM world
WHERE population > 10E6
GROUP BY continent

--#8
--List the continents that have a total population of at least 100 million. 

SELECT continent FROM world
GROUP BY continent
HAVING SUM(population) > 100E6