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SELECT practicing queryies on SQLzoo.net

Piotr Sutor edited this page Aug 31, 2020 · 3 revisions

SQLzoo - SELECT within SELECT tutorial

  1. Show the name and the population of each country in Europe. Show the population as a percentage of the population of Germany. The format should be Name, Percentage for example:

SELECT name, CONCAT(ROUND(100*(population / (SELECT population FROM world WHERE name='Germany')),0),'%') FROM world WHERE continent = 'Europe'

this one rounds to 0 decimal places but prints like 10 zeros when MsSQL selected, MySQL reults are as expected, nicely rounded no decimals. CONCAT can be replaced by || or + on some SQL versions.

  1. Which countries have a GDP greater than every country in Europe? [Give the name only.] (Some countries may have NULL gdp values)

SELECT name FROM world WHERE gdp > ALL(SELECT gdp FROM world
WHERE gdp > 0 AND continent = 'Europe') EZ

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