SUM and COUNT

注意：where語句中對錶示條件的需要用單引號，下面的譯文使用的是有道翻譯如有不正確，請直接投訴有道

01.Show the totalpopulationof the world.

譯文：展示世界總人口。

SELECT SUM(population) FROM world

02.List all the continents - just once each.

譯文：列出所有的大陸——每個大陸只列出一次。

SELECT DISTINCT continent FROM world

03.Give the total GDP of Africa

譯文：看看非洲的GDP總量

SELECTSUM(gdp)FROM worldWHERE continent ='Africa'

04.How many countries have anareaof at least 1000000

譯文：有多少國家的面積至少有100萬。

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

05.What is the totalpopulationof ('Estonia', 'Latvia', 'Lithuania')

譯文：愛沙尼亞、拉脫維亞、立陶宛的總人口是多少?

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

06.For eachcontinentshow thecontinentand number of countries.

譯文：表示每個洲的洲數和國家數。

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

07.For eachcontinentshow thecontinentand number of countries with populations of at least 10 million.

譯文：每一洲顯示人口至少為1 000萬的洲和國家數目。

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

08.List the continents thathavea total population of at least 100 million.

譯文：列出總人口至少為1億的大洲。

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

練習網址：https://sqlzoo.net/wiki/SUM_and_COUNT

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