population

-- How many entries in the database are from Africa?

SELECT COUNT(*) FROM countries WHERE
continent = 'Africa';

-- What was the total population of Oceania in 2005?

SELECT SUM(population) FROM population_years
INNER JOIN countries ON
countries.id = population_years.country_id
WHERE YEAR = 2005
AND continent = 'Oceania';

-- What is the average population of countries in South America in 2003?

SELECT AVG(population) FROM population_years
INNER JOIN countries ON
countries.id = population_years.country_id
WHERE YEAR = 2003
AND continent = 'South America';

-- What country had the smallest population in 2007?

SELECT MIN(population), name FROM population_years
INNER JOIN countries ON
countries.id = population_years.country_id
WHERE YEAR = 2007;

-- What is the average population of Poland during the time period covered by this dataset?

SELECT AVG(population), name FROM population_years
INNER JOIN countries ON
countries.id = population_years.country_id
WHERE name = 'Poland';

-- How many countries have the word "The" in their name?

SELECT COUNT(*) FROM countries
WHERE name LIKE "%The%";

-- What was the total population of each continent in 2010?

SELECT SUM(population), continent FROM population_years
INNER JOIN countries ON
countries.id = population_years.country_id
WHERE YEAR = 2010
GROUP BY continent;