# Difference between revisions of "SUM and COUNT/ja"

 Language: [[:{{#invoke:String|sub|SUM and COUNT/ja ``` |1 |Expression error: Unrecognized punctuation character "{". ``` }}|English]]

このチュートリアルでは COUNT, SUM , AVG などの集計関数を扱う。集計関数は多数の値から１つの値を計算する。例えば、関数 SUM は 2, 4 ,5 から1つの値 11 を計算する。

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

## 世界人口のトータル

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

## 大陸のリスト

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

## アフリカのGDP

アフリカAfrica の各国のgdpの合計を求める。

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

## 大きな国の数

```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

You may want to look at these examples: Using GROUP BY and HAVING.

## Counting the countries of each continent

For each continent show the continent and number of countries.

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

## Counting big countries in each 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)
```

## Counting big continents

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

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

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

The next tutorial looks at the Table Tennis database. It shows how queries may use records from two related tables.