World Populations SQL Practice II

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

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

SELECT id, continent
FROM countries
GROUP BY continent;

SELECT *
FROM population_years
LIMIT 10;

SELECT SUM(population) AS 'Population of Oceana in 2005 (in millions)'
FROM population_years
WHERE year = 2005 AND country_id = 213;

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

SELECT AVG(population_years.population) AS 'Poland Average Population'
FROM countries 
JOIN population_years
  ON countries.id = population_years.country_id
WHERE countries.name = 'Poland';

SELECT COUNT(*) AS 'Countries containing The'
FROM countries
WHERE name LIKE '%The%';

SELECT countries.continent, SUM(population_years.population) AS 'Pupulation in 2010 (in millions)'
FROM countries 
JOIN population_years
 ON countries.id = population_years.country_id
WHERE year = 2010
GROUP BY countries.continent;