SQLZOO 05

SUM and COUNT

1. Show the total population of the world.

SELECT SUM(population)
FROM world;

2. List all the continents - just once each.

SELECT continent
FROM world
GROUP BY continent;

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 >= 10000000
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) >= 100000000;