SQLZOO习题详解(05)——SELECT within SELECT

Posted 2021-05-18 谷哥的小弟

---

版权声明

• 本文原创作者：谷哥的小弟
• 作者博客地址：http://blog.csdn.net/lfdfhl

---

world表

world表如下：

链接地址

https://napier.sqlzoo.net/wiki/SELECT_within_SELECT_Tutorial

SQL练习

01、查询人口数量比Russia人口数量多的国家的名字

SELECT name FROM world WHERE population > (SELECT population FROM world WHERE name='Russia')

02、查询人均GDP比United Kingdom高且属于欧洲Europe的国家的名字

SELECT name FROM world
WHERE gdp / population > (SELECT gdp / population FROM world WHERE name = 'United Kingdom') AND continent = 'Europe'

03、查询阿根廷Argentina及澳大利亚Australia所在的洲份中的国家的名称及其所属洲；并按照国家名称排序

SELECT name, continent
FROM world
WHERE continent IN (
	SELECT continent
	FROM world
	WHERE name IN ('Argentina', 'Australia')
)
ORDER BY name

04、查询人口数量比加拿大Canada多，但比波兰Poland少的国家的名称及其人口数量

SELECT name, population
FROM world
WHERE population > (
		SELECT population
		FROM world
		WHERE name = 'Canada'
	)
	AND population < (
		SELECT population
		FROM world
		WHERE name = 'Poland'
	)

SELECT name, population
FROM world
WHERE population BETWEEN (
		SELECT population
		FROM world
		WHERE name = 'Canada'
	)
	AND (
		SELECT population
		FROM world
		WHERE name = 'Poland'
	)
	AND name NOT IN ('Canada', 'Poland')

05、查询所属洲为Europe的国家的名称及其人口数量。其中，人口数量以德国的人口数量的百分比作显示。

SELECT name
	, concat(round(100 * population / (
		SELECT population
		FROM world
		WHERE name = 'Germany'
	), 0), '%') AS percentage
FROM world
WHERE continent = 'Europe'

06、查询非欧洲Europe国家中GDP比所有欧洲Europe国家都要高的国家的名称

SELECT name
FROM world
WHERE gdp >= ALL (
		SELECT gdp
		FROM world
		WHERE gdp >= 0 AND continent = 'Europe'
	)
	AND continent != 'Europe'

07、在每一個州中找出该洲国土面积最大的国家。请列出这些国家的continent，name，area

SELECT continent, name, area
FROM world AS a
WHERE area >= ALL (
	SELECT area
	FROM world AS b
	WHERE b.continent = a.continent AND area > 0
)

08、查询每个洲的洲名，以及在该洲continent中按照字母排序的首位国家。

SELECT continent, name
FROM world AS a
WHERE name <= ALL (
	SELECT name
	FROM world AS b
	WHERE b.continent = a.continent
)

09、查询洲continent中所有国家人口均小于或等于25000000的洲；并列出该洲中的国家名称，人口数量，洲名

SELECT name, continent, population
FROM world AS a
WHERE 25000000 >= ALL (
	SELECT population
	FROM world AS b
	WHERE a.continent = b.continent AND b.population > 0
)

10、某些国家的人口数量是同洲份的其它任意国家的3倍或以上。请查询这些国家的名称以及所属洲continent

SELECT name, continent
FROM world AS a
WHERE population > ALL (
	SELECT population * 3
	FROM world AS b
	WHERE a.continent = b.continent AND a.name != b.name
)