SQL ZOO我的答案2之SELECT from World
SELECT from World
3、找出有至少200百萬(2億)人口的國家名稱，及人均國內生產總值。
SELECT name,gdp/population FROM world WHERE population>200000000;
4、顯示'South America'南美洲大陸的國家名字和以百萬為單位人口數。
SELECT name,population/1000000 FROM world WHERE continent = 'South America';
5、顯示法國，德國，義大利(France, Germany, Italy)的國家名稱和人口。
SELECT name,population FROM world WHERE name IN('France','Germany','Italy');
6、包含單詞“United”為名稱的國家。
SELECT name FROM world WHERE name LIKE '%United%';
7、為大國的兩種方式：如果它有3百萬平方公里以上的面積，或擁有250百萬(2.5億)以上人口。 展示大國的名稱，人口和麵積
SELECT name,population,area FROM world WHERE area>3000000 OR population>250000000;
8、美國、印度和中國(USA, India, China)是人口又大，同時面積又大的國家。排除這些國家。
顯示以人口或面積為大國的國家，但不能同時兩者
SELECT name,population,area FROM world WHERE name NOT IN ('United States', 'India', 'China') AND ((area > 3000000 AND population <= 50000000) OR (area <= 000000 AND population > 250000000));
或者
SELECT name,population,area FROM world WHERE (area>=3000000 OR population >=250000000) AND NOT name IN (SELECT name FROM world WHERE area>=3000000 AND population >=250000000);
9、對於南美顯示以百萬計人口，以十億計2位小數GDP。
SELECT name, ROUND(population/1000000,2),ROUND(gdp/1000000000,2) FROM world WHERE continent = 'South America';
10、顯示萬億元國家的人均國內生產總值，四捨五入到最近的$ 1000。
SELECT name,ROUND(gdp/population,-3)FROM world WHERE gdp>1000000000000;
11、Show the name - but substitute Australasia for Oceania - for countries beginning with N.
SELECT name
,CASE WHEN continent='Oceania' THEN 'Australasia'
ELSE continent
END
FROM world
WHERE name LIKE 'N%';
12、Show the name and the continent - but substitute Eurasia for Europe and Asia; substitute America - for each country in North America or South America or Caribbean. Show countries beginning with A or B.
SELECT name,
CASE WHEN continent IN('Europe','Asia')
THEN 'Eurasia'
WHEN continent IN('North America','South America','Caribbean')
THEN 'America'
ELSE continent END
FROM world
WHERE name LIKE 'A%' OR name LIKE 'B%';
13、Put the continents right...
Oceania becomes Australasia
Countries in Eurasia and Turkey go to Europe/Asia
Caribbean islands starting with 'B' go to North America, other Caribbean islands go to South America
Show the name, the original continent and the new continent of all countries.
SELECT name,continent,
CASE WHEN continent = 'Oceania'
THEN 'Australasia'
WHEN continent IN ('Eurasia', 'Turkey')
THEN 'Europe/Asia'
WHEN continent = 'Caribbean' AND name LIKE 'B%'
THEN 'North America'
WHEN continent = 'Caribbean' THEN 'South America'
ELSE continent
END
FROM world
ORDER BY name ASC;（按字母排序了）
或者
SELECT name,continent,
CASE WHEN continent IN ('Eurasia', 'Turkey')
THEN 'Europe/Asia'
WHEN continent = 'Oceania'
THEN 'Australasia'
WHEN continent = 'Caribbean'
THEN
CASE
WHEN name LIKE 'B%'
THEN 'North America'
ELSE 'South America'
END（疊加了，理解成if。。。else。。。）
ELSE continent
END
FROM world
ORDER BY name ASC;
（此處ORDER BY name ASC是參考別人的）