Difference between revisions of "SQLZOO:SELECT from WORLD Tutorial"

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Show the per-capita GDP for those countries with a GDP of at least one trillion. Round this value to the nearest 100.
+
Show the per-capita GDP for those countries with a GDP of at least one trillion (1000000000000 12 zeros). Round this value to the nearest 1000.
<p class=imper>Show per-capita GDP for the trillion dollar countries to the nearest $100.</p>  
+
<p class=imper>Show per-capita GDP for the trillion dollar countries to the nearest $1000.</p>  
 
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</source>
 
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<source lang='sql' class='ans'>
select name, ROUND(gdp/population,-2)
+
select name, ROUND(gdp/population,-3)
 
from world
 
from world
 
where
 
where

Revision as of 17:03, 5 May 2015

namecontinentarea populationgdp
AfghanistanAsia6522302550010020343000000
AlbaniaEurope28748 2831741 12960000000
AlgeriaAfrica2381741 37100000 188681000000
AndorraEurope46878115 3712000000
AngolaAfrica1246700 20609294 100990000000
...

Country Profile

In this tutorial you will use the SELECT command on the table World:

Read the notes about this table. Observe the result of running a simple SQL command.

SELECT name, continent, population FROM world
SELECT name, continent, population FROM world

How to use WHERE to filter records. Show the name for the countries that have a population of at least 200 million. 200 million is 200000000, there are eight zeros.

SELECT name FROM world
WHERE population>250000000
SELECT name FROM world
WHERE population>200000000


Give the name and the per capita GDP for those countries with a population of at least 200 million.

per capita GDP is the GDP divided by the population GDP/population

SELECT name, gdp/population FROM world
  WHERE population > 200000000

Show the name and population in millions for the countries of the continent 'South America'. Divide the population by 1000000 to get population in millions.

SELECT name, population/1000000 FROM world
  WHERE continent='South America'

Show the name and population for France, Germany, Italy

SELECT name, population FROM world
  WHERE name IN ('France','Germany','Italy')

Show the countries which have a name that includes the word 'United'

SELECT name FROM world
  WHERE name LIKE '%United%'

Two ways to be big: A country is big if it has an area of more than 3 million sq km or it has a population of more than 250 million.

Show the countries that are big by area or big by population. Show name, population and area.

select name,population,area
from world
where area>3000000
or population>250000000

USA and China are big in population and big by area. Exclude these countries.

Show the countries that are big by area or big by population but not both. Show name, population and area.

select name, population,area
from world
where
(population>250000000 or area>3000000)
and not(population>250000000 and area>3000000)

Show the per-capita GDP for those countries with a GDP of at least one trillion (1000000000000 12 zeros). Round this value to the nearest 1000.

Show per-capita GDP for the trillion dollar countries to the nearest $1000.

select name, ROUND(gdp/population,-3)
from world
where
gdp>1000000000000

Show the name and population in millions and the GDP in billions for the countries of the continent 'South America'. Use the ROUND function to show the values to two decimal places.

For South America show population in millions and GDP in billions to 2 decimal places.
Divide by 1000000 (6 zeros) for millions. Divide by 1000000000 (9 zeros) for billions.
SELECT name, ROUND(population/1000000,2),
             ROUND(gdp/1000000000,2)
  FROM world
 WHERE continent='South America'

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