SQLZOO练习三--SELECT within SELECT Tutorial
This tutorial looks at how we can use SELECT statements within SELECT statements to perform more complex queries.
name | continent | area | population | gdp |
---|---|---|---|---|
Afghanistan | Asia | 652230 | 25500100 | 20343000000 |
Albania | Europe | 28748 | 2831741 | 12960000000 |
Algeria | Africa | 2381741 | 37100000 | 188681000000 |
Andorra | Europe | 468 | 78115 | 3712000000 |
Angola | Africa | 1246700 | 20609294 | 100990000000 |
... |
1、Bigger than Russia
获取人口比俄罗斯多的国家名字
List each country name where the population is larger than that of 'Russia'.
select name
from world
where population>(select population from world where name='Russia');
2、Richer than UK
获取欧洲国家中,人均gdp高于United Kingdom的国家名称。
Show the countries in Europe with a per capita GDP greater than 'United Kingdom'.
select name from world
where continent='Europe' and gdp/population>(select gdp/population from world where name='United Kingdom');
3、Neighbours of Argentina and Australia
获取国家名称及所在大陆名称,条件是包含阿根廷或者澳大利亚的大陆,按照国家名称升序排序。
List the name and continent of countries in the continents containing either Argentina or Australia. Order by name of the country.
select name,continent
from world
where continent in(select continent from world where name in('Argentina','Australia'))
order by name;
4、Between Canada and Poland
获取人口大于加拿大,同时人口小于波兰的国家名称、人口。
Which country has a population that is more than Canada but less than Poland? Show the name and the population.
select name,population
from world
where population > (select population from world where name ='Canada') and population < (select population from world where name='Poland');
5、Percentages of Germany
获取欧洲各国家名称,以及各国家人口/德国人口的百分比。
Germany (population 80 million) has the largest population of the countries in Europe. Austria (population 8.5 million) has 11% of the population of Germany.
Show the name and the population of each country in Europe. Show the population as a percentage of the population of Germany.
select name,concat(round((population/(select population from world where name='Germany'))*100,0),'%') as percentage
from world
where continent='Europe';
解题思路:️获取德国人口的select语句;️用concat函数,转换成字符串后拼接百分号。
6、Bigger than every country in Europe
获取超过欧洲任何一个国家gdp的国家名字。
Which countries have a GDP greater than every country in Europe? [Give the name only.] (Some countries may have NULL gdp values)
select name
from world
where gdp>(select max(gdp) from world where continent='Europe');
解题思路:超过欧洲任何一个国家gdp,这里用到聚合函数max(gdp),意思是取欧洲国家gdp的最大值。
7、Largest in each continent
获取每个大洲面积最大的国家,展示所在大陆、国家名称、面积。
Find the largest country (by area) in each continent, show the continent, the name and the area:
SELECT continent, name, area FROM world x
WHERE area >= ALL
(SELECT area FROM world y
WHERE y.continent=x.continent
AND area>0);
8、First country of each continent (alphabetically)
select continent,name
from world x
where name=(select min(name) from world y where x.continent=y.continent);
9、Difficult Questions That Utilize Techniques Not Covered In Prior Sections
Find the continents where all countries have a population <= 25000000. Then find the names of the countries associated with these continents. Show name, continent and population.
select name,continent,population
from world
where continent=(select continent from world
group by continent
having max(population)<=25000000);
解题思路:每个大洲全部国家人口都要小于2500万,用聚合函数max()函数。注意,这时候,不能用where,必须用having,因为where不能和聚合函数一起使用。
10、获取同一大洲,该国家面积大于等于其他所有国家3倍以上的国家名称和大洲名称。
Some countries have populations more than three times that of any of their neighbours (in the same continent). Give the countries and continents.
select name,continent
from world x
where population>=ALL(select population*3 from world y
where x.continent=y.continent and x.name!=y.name and population>0);
解题思路:
SQLZOO练习三--SELECT within SELECT Tutorial的更多相关文章
- sqlzoo - SELECT from WORLD Tutorial 答案
01.SELECT from WORLD Tutorial 01.显示所有国家的名称,大洲和人口. SELECT name, continent, population FROM world; 02. ...
- SELECT within SELECT Tutorial -- SQLZOO
SELECT within SELECT Tutorial 注意:where语句中对表示条件的需要用单引号, 下面的译文使用的是有道翻译如有不正确,请直接投诉有道 01.List each count ...
- sqlzoo刷题 SELECT from Nobel Tutorial
SELECT from Nobel Tutorial 1.Change the query shown so that it displays Nobel prizes for 1950. SELEC ...
- SELECT from Nobel Tutorial
02.SELECT from Nobel Tutorial 注意:where语句中对表示条件的需要用单引号, 下面的译文使用的是有道翻译如有不正确,请直接投诉有道 01.Change the quer ...
- 关于Select * 与Select 字段名 的问题!
[转]http://blog.csdn.net/tongyu2009/article/details/8252418 1.SELECT * 语句取出表中的所有字段,不论该字段的数据对调用的应用程序是否 ...
- Insert Into select 与 Select Into 哪个更快?
在平常数据库操作的时候,我们有时候会遇到表之间数据复制的情况,可能会用到INSERT INTO SELECT 或者 SELECT INTO : 那么二者语法上有什么区别?性能上又如何呢? 围绕着这两个 ...
- oracle 中 insert select 和 select insert 配合使用
Insert Into select 与 Select Into 哪个更快? 在平常数据库操作的时候,我们有时候会遇到表之间数据复制的情况,可能会用到INSERT INTO SELECT 或者 SEL ...
- SQL笔记1:SELECT及SELECT高级应用
T-SQL笔记1:SELECT及SELECT高级应用 本章摘要 1:安装AdventureWorks 2:基本运算符和表达式 3:between 4:like 5:escape 6:TOP 7:G ...
- PHP MySQL Select 之Select
从数据库表中选取数据 SELECT 语句用于从数据库中选取数据. 语法 SELECT column_name(s) FROM table_name 注释:SQL 语句对大小写不敏感.SELECT 与 ...
- select * from (select P.*,ROWNUM RN FROM(select * from Mp_Relatedart where pubbaseid=785 order by ID ASC )P)M WHERE M.RN>2 and M.RN <= 7
select * from (select P.*,ROWNUM RN FROM(select * from Mp_Relatedart where pubbaseid=785 order by ID ...
随机推荐
- 【mq】从零开始实现 mq-03-引入 broker 中间人
前景回顾 [mq]从零开始实现 mq-01-生产者.消费者启动 [mq]从零开始实现 mq-02-如何实现生产者调用消费者? [mq]从零开始实现 mq-03-引入 broker 中间人 上一节我们学 ...
- 视网膜血管分割代码(Pytorch实现)
创建日期: 2021-12-24 17:00:00 update log(2021.12.24):B站视频删除了,回放看了一下,讲的不太行......2333,时间过得真快,转眼就是2022年了啊 2 ...
- css实现气泡提示框三角及css中drop-shadow的使用
css 做一个弹出气泡,样式怎么设计? 难点: 要实现白色三角型,可以在伪元素before和after上设置一个黑.一个白三角形,白三角形会挡住黑的,从而实现. &::before, & ...
- vue-router实现原理及简易demo
自定义路由demo,git地址: git@github.com:xsk-walter/Vue-router.git 一.router基本使用 ① 创建和路由相关的组件 ②Vue.use(vueRout ...
- Centos7上安装python3.7
Centos7安装python3.7 由于python2和python3在很大程度上有些不同,因为需要,就以决定安装python3.x的版本,但由于Centos上自安装的就是pyhton2.6.所以在 ...
- 每天一个 HTTP 状态码 前言
前前言 在重新开始写博文(其实大多也就最多算是日常笔记小结)之际,就想着从短小精悍的文章入手,就想到了 HTTP 状态码.另外,记得很久之前,看过一个<每天一个 Linux 命令>系列文章 ...
- 关于『进击的Markdown』:第四弹
关于『进击的Markdown』:第四弹 建议缩放90%食用 美人鱼(Mermaid)悄悄的来,又悄悄的走,挥一挥匕首,不留一个活口 又是漫漫画图路... 女士们先生们,大家好! 我们要接受Markd ...
- Python 微博搜索爬虫
微博搜索爬虫 网页分析 由于网页端反爬虫机制比较完善所以才去移动端进行爬虫. url地址:https://m.weibo.cn/ 搜索框,输入关键词进行搜索 对网页进行抓包,找到相关数据 查看数据是否 ...
- MVC - Request对象的主要方法
MVC - Request对象的主要方法 setAttribute(String name,Object):设置名字为name的request的参数值 getAttribute(String name ...
- 开源项目 PM 浅谈如何设计官网
有用户反馈进入官网首页光秃秃的一片,大家忙着做产品,忽略了官网的建设,惭愧惭愧. 确实,极简风格和极其简单还是有很大区别的. 旧的 Web 端 除了极其简单之外,它还有一个小问题, ...