# Difference between revisions of "SUM and COUNT"

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### World 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.

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

## Total world population

Show the total population of the world.

```world(name, continent, area, population, gdp)
```
```SELECT SUM(population)
FROM world
```
```SELECT SUM(population)
FROM world
```

## List of continents

List all the continents - just once each.

```
```
```SELECT DISTINCT(continent)
FROM world
```

## GDP of Africa

Give the total GDP of Africa

```
```
```SELECT SUM(gdp)
FROM world
WHERE continent = 'Africa'
```

## Count the big countries

How many countries have an area of at least 1000000

```
```
```SELECT COUNT(name)
FROM world
WHERE area >= 1000000
```

## Baltic states population

What is the total population of ('Estonia', 'Latvia', 'Lithuania')

```
```
```SELECT SUM(population)
FROM world
WHERE name IN ('Estonia', 'Latvia', 'Lithuania')
```

Using GROUP BY and HAVING.

For each continent show the continent and number of countries.

```
```
```SELECT continent, COUNT(name)
FROM world
GROUP BY(continent)
```

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

```
```
```SELECT continent, COUNT(name)
FROM world
WHERE population >= 10000000
GROUP BY(continent)
```

List the continents that have a total population of at least 100 million.

```
```
```SELECT continent
FROM world
GROUP BY continent
HAVING SUM(population)>= 100000000
```