sqlzoo练习1

皮大大

发布于 2021-03-02 16:31:59

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文章被收录于专栏：机器学习/数据可视化机器学习/数据可视化

开始进行SQL的练习，选择了sqlzoo网站

表结构

练习题

主要是练习where语句的使用

-- 1
SELECT population FROM world
WHERE name = 'Germany'

-- 2
SELECT name, population FROM world
WHERE name IN ('Sweden', 'Norway','Denmark');

-- 3
SELECT name, area FROM world
WHERE area BETWEEN 200000 AND 250000

quiz

产生下表的结果

select name, population
from world
wher populantion between 1000000 and 1250000

通配符使用

select name, population
from world
where name like "AL%"  -- AL开头的名字

Select the code which shows the countries that end in A or L

select name
from world
where name like "a%" or name like "%l"

代码运行结果

select name, length(name)
from world
where length(name)=5 and region="Europe"

代码运行结果

select name, area*2
from world
where population = 64000

Select the code that would show the countries with an area larger than 50000 and a population smaller than 10000000

select name, area, population
from world
where area > 50000 and population < 1000000;

Select the code that shows the population density of China, Australia, Nigeria and France

笔记：题目中要求的是人口密度

select name, population / area
from world
where name in ('China', 'Nigeria', 'France', 'Australia')

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原始发表：2020-1-13，如有侵权请联系 cloudcommunity@tencent.com 删除

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sqlzoo练习1

sqlzoo练习1

表结构

练习题

quiz

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