# Difference between revisions of "SUM and COUNT"

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− | + | <h3>BBC Country Profile: Aggregate functions</h3> | |

This tutorial is about aggregate functions such as COUNT, SUM and AVG. An aggregate function takes many values and delivers just one value. For example the function SUM would aggregate the values 2, 4 and 5 to deliver the single value 11. | This tutorial is about aggregate functions such as COUNT, SUM and AVG. An aggregate function takes many values and delivers just one value. For example the function SUM would aggregate the values 2, 4 and 5 to deliver the single value 11. | ||

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+ | <h2>What next</h2> | ||

+ | <p>[[The nobel table can be used to practice more SUM and COUNT functions.]]</p> | ||

+ | <p>[http://sqlzoo.net/w/index.php/The_JOIN_operation The next tutorial is looks at the Table Tennis database. It shows how queries may use records from two related tables.] |

## Revision as of 09:22, 11 July 2012

### BBC Country Profile: Aggregate functions

This tutorial is about aggregate functions such as COUNT, SUM and AVG. An aggregate function takes many values and delivers just one value. For example the function SUM would aggregate the values 2, 4 and 5 to deliver the single value 11.

## Exercises

Using SUM, Count, MAX, DISTINCT and ORDER BY.

Show the total **population** of the world.

bbc(name,region,area,population,gdp)

SELECT SUM(population) FROM bbc

SELECT SUM(population) FROM bbc

List all the regions - just once each.

SELECT DISTINCT(region) FROM bbc

Give the total GDP of Africa

SELECT SUM(gdp) FROM bbc WHERE region = 'Africa'

How many countries have an **area** of at least 1000000

SELECT COUNT(region) FROM bbc WHERE area >= 1000000

What is the total **population** of ('France','Germany','Spain')

SELECT SUM(population) FROM bbc WHERE name IN('France','Germany','Spain')

For each **region** show the **region** and number of countries.

SELECT region, COUNT(name) FROM bbc GROUP BY(region)

For each **region** show the **region** and number of countries with populations of at least 10 million.

SELECT region, COUNT(name) FROM bbc WHERE population >= 10000000 GROUP BY(region)

List the regions with total populations of at least 100 million.

SELECT region FROM bbc GROUP BY region HAVING SUM(population)>= 100000000

## What next

The nobel table can be used to practice more SUM and COUNT functions.