sqlzoo 5.SUM and COUNT 答案

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原题链接：https://sqlzoo.net/wiki/SUM_and_COUNT

其他题解连接：https://blog.csdn.net/aiqiyizz/article/details/109057732

题解对应的是英文版题目。

5 SUM and COUNT

5.1 Total world population

SELECT SUM(population)
FROM world
1

5.2 List of continents

SELECT DISTINCT continent
FROM world
1

5.3 GDP of Africa

SELECT SUM(gdp)
FROM world
WHERE continent = 'Africa'
1
2

5.4 Count the big countries

SELECT COUNT(*)
FROM world
WHERE area >= 1000000
1
2

5.5 Baltic states population

SELECT SUM(population)
FROM world
WHERE name IN ('Estonia','Latvia','Lithuania')
1
2

5.6 Counting the countries of each continent

SELECT continent, COUNT(name)
FROM world
GROUP BY continent
1
2

5.7 Counting big countries in each continent

SELECT continent, COUNT(name)
FROM world
WHERE population >= 10000000
GROUP BY continent
1
2
3

5.8 Counting big continents

SELECT continent
FROM world
GROUP BY continent
HAVING SUM(population) >= 100000000
1
2
3