sqlzoo 5. SUM and COUNT answer

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Link to the original title: https://sqlzoo.net/wiki/SUM_and_COUNT

Other question solution links: https://blog.csdn.net/aiqiyizz/article/details/109057732

The solution corresponds to the English version.

5 SUM and COUNT

5.1 Total world population

SELECT SUM(population)
FROM world

5.2 List of continents

SELECT DISTINCT continent
FROM world

5.3 GDP of Africa

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

5.4 Count the big countries

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

5.5 Baltic states population

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

5.6 Counting the countries of each continent

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

5.7 Counting big countries in each continent

SELECT continent, COUNT(name)
FROM world
WHERE population >= 10000000
GROUP BY continent

5.8 Counting big continents

SELECT continent
FROM world
GROUP BY continent
HAVING SUM(population) >= 100000000