SQLZoo

Introduction

紀錄一些 SQL 常用的code，做了 SQLZoo 的題目，資料像是

name	continent	area	population	gdp	capital	tld	flag
Afghanistan	Asia	652230	25500100	20364000000	Kabul	.af	//upload.wikimedia.org/wikipedia/commons/9/9a/Flag_of_Afghanistan.svg
Albania	Europe	28748	2821977	12044000000	Tirana	.al	//upload.wikimedia.org/wikipedia/commons/3/36/Flag_of_Albania.svg
Algeria	Africa	2381741	38700000	207021000000	Algiers	.dz	//upload.wikimedia.org/wikipedia/commons/7/77/Flag_of_Algeria.svg
Andorra	Europe	468	76098	3222000000	Andorra la Vella	.ad	//upload.wikimedia.org/wikipedia/commons/1/19/Flag_of_Andorra.svg
…	…	…	…	…	…	…	…

習題

SELECT from WORLD

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#1.
SELECT name, continent, population FROM world;


#2.
SELECT name FROM world
WHERE POPULATION > 200000000;


#3. 
SELECT name, GDP / population AS per_capita_GDP
FROM world
WHERE population > 200000000;


#4.
SELECT name,  population/1000000  AS population_in_millions
FROM world
WHERE continent = "South America";


#5.
SELECT name, population
FROM world
WHERE name IN ('France', 'Germany', 'Italy');


#6.
SELECT name FROM world
WHERE name LIKE '%United%';


#7.
SELECT name,  population,area FROM world
WHERE population >250000000 or area>3000000;

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