# SELECT from WORLD Tutorial
[Link](https://sqlzoo.net/wiki/SELECT_from_WORLD_Tutorial)
1. [Read the notes about this table.](https://sqlzoo.net/wiki/Read_the_notes_about_this_table.) Observe the result of running this SQL command to show the name, continent and population of all countries.
```sql
SELECT name, continent, population FROM world
```
2. [How to use WHERE to filter records.](https://sqlzoo.net/wiki/WHERE_filters) Show the name for the countries that have a population of at least 200 million. 200 million is 200000000, there are eight zeros.
```sql
SELECT name FROM world WHERE population >= 200000000
```
3. Give the `name` and the per capita GDP for those countries with a `population` of at least 200 million. \
HELP: How to calculate per capita GDP (per capita GDP is the GDP divided by the population GDP/population)
```sql
SELECT name, GDP/population
FROM world
WHERE population >= 200000000
```
4. 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.
```sql
SELECT name, population/1000000
FROM world
WHERE continent ='South America'
```
5. Show the `name` and `population` for France, Germany, Italy
```sql
SELECT name, population
FROM world
WHERE name IN ('France','Germany','Italy')
```
6. Show the countries which have a `name` that includes the word 'United'
```sql
SELECT name
FROM world
WHERE name LIKE '%United%'
```
7. 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.
```sql
SELECT name, population, area
FROM world
WHERE area > 3000000 OR population > 250000000
```
8. Exclusive OR (XOR). Show the countries that are big by area (more than 3 million) or big by population (more than 250 million) but not both. Show name, population and area.
* Australia has a big area but a small population, it should be included.
* Indonesia has a big population but a small area, it should be included.
* China has a big population and big area, it should be excluded.
* United Kingdom has a small population and a small area, it should be excluded.
SELECT name, population, area
FROM world
WHERE (area > 3000000 OR population > 250000000)
AND name NOT IN (SELECT name
FROM world
WHERE area > 3000000 AND population > 250000000)
9. Show the `name` and `population` in millions and the GDP in billions for the countries of the `continent` 'South America'. Use the [ROUND](https://sqlzoo.net/wiki/ROUND) function to show the values to two decimal places. \
For South America show population in millions and GDP in billions both to 2 decimal places.
```sql
SELECT name, ROUND(population/1000000,2), ROUND(GDP/1000000000,2)
FROM world
WHERE continent = 'South America'
```
10. Show the `name` and per-capita GDP for those countries with a GDP of at least one trillion (1000000000000; that is 12 zeros). Round this value to the nearest 1000.\
Show per-capita GDP for the trillion dollar countries to the nearest $1000.
```sql
SELECT name, ROUND(GDP/population,-3)
FROM world
WHERE GDP >= 1000000000000
```
11. Greece has capital Athens. Each of the strings 'Greece', and 'Athens' has 6 characters.\
Show the name and capital where the name and the capital have the same number of characters.
* You can use the [LENGTH](https://sqlzoo.net/wiki/LENGTH) function to find the number of characters in a string
For Microsoft SQL Server the function LENGTH is LEN
```sql
SELECT name, LENGTH(name), capital, LENGTH(capital)
FROM world
WHERE LENGTH(name) = LENGTH(capital)
```
12. The capital of Sweden is Stockholm. Both words start with the letter 'S'. \
Show the name and the capital where the first letters of each match. Don't include countries where the name and the capital are the same word.\
\- You can use the function [LEFT](https://sqlzoo.net/wiki/LEFT) to isolate the first character.\
\- You can use `<>` as the NOT EQUALS operator.
```sql
SELECT name, capital
FROM world
WHERE name <> capital
AND LEFT(name,1) = LEFT(capital,1)
```
13. Equatorial Guinea and Dominican Republic have all of the vowels (a e i o u) in the name. They don't count because they have more than one word in the name.\
Find the country that has all the vowels and no spaces in its name.
* You can use the phrase `name NOT LIKE '%a%'` to exclude characters from your results.
* The query shown misses countries like Bahamas and Belarus because they contain at least one 'a'
```sql
SELECT name
FROM world
WHERE name LIKE '%a%'
AND name LIKE '%e%'
AND name LIKE '%o%'
AND name LIKE '%u%'
AND name LIKE '%i%'
AND name NOT LIKE '% %'
```
---
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