sqlzoo练习系列(八)——群组函数之SUM和COUNT
【Tips】
- sqlzoo官网链接:
- 每个系列开头介绍所用表及其信息
- 每道题均测试通过,含有题目描述、代码和结果
- 题目为自己简写,最好在官网查看具体题目
- 部分测试结果不完整,仅为一部分截图
群组函数之SUM和COUNT练习链接:
- name:国家名称
- continent:洲
- area:面积
- population:人口
- gdp:国内生产总值
1.展示世界总人口
SELECT SUM(population) FROM world
SELECT DISTINCT continent FROM world
SELECT SUM(GDP) FROM world WHERE continent='Africa'
SELECT COUNT(name) FROM world WHERE area >=1000000
SELECT SUM(population) FROM world WHERE name IN ('France','Germany','Spain')
SELECT continent,COUNT(name) FROM world GROUP BY continent
SELECT continent,COUNT(name) FROM world WHERE population >= 10000000 GROUP BY continent
SELECT continent FROM world GROUP BY continent HAVING SUM(population)>=100000000