Difference between revisions of "SUM and COUNT/ja"

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以下の例を見ておくとよい。
 
以下の例を見ておくとよい。
 
<p>[[Using SUM, Count, MAX, DISTINCT and ORDER BY/ja]].</p>
 
<p>[[Using SUM, Count, MAX, DISTINCT and ORDER BY/ja]].</p>
==Total world population==
+
==世界人口のトータル==
 
<div class='qu'>
 
<div class='qu'>
 
Show the total '''population''' of the world.
 
Show the total '''population''' of the world.

Revision as of 16:51, 18 April 2018

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

世界各国のプロフィール: 集計関数

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
...

以下の例を見ておくとよい。

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

世界人口のトータル

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

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.