SQLZOO:SELECT from WORLD Tutorial/zh

SQLZOO:SELECT from WORLD Tutorial/zh

8. 顯示以人口或面積為大國的國家，但不能同時兩者。顯示國家名稱，人口和面積。select name,population,area
from world
where (area > 3000000 and population <= 250000000) or (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 Bselect 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'and name not like 'B%' then  'South America'
else continent  end
from world
order by name