5 SUM and COUNT
作者:互联网
1. Show the total population of the world
SELECT SUM(population) FROM world;
2. List all the continents - just once each
select distinct continent from world;
3. Give the total GDP of Africa
select sum(gdp) from world
where continent = 'Africa';
4. How many countries have an area of at least 1000000
select count(name) from world
where area > 1000000;
5. What is the total population of (‘Estonia’, ‘Latvia’, ‘Lithuania’)
select sum(population) from world
where name in('Estonia', 'Latvia', 'Lithuania');
6. For each continent show the continent and number of countries
select continent,count(name) from world
group by continent;
7. 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;
8. List the continents that have a total population of at least 100 million
select continent from world
group by continent
having sum(population) >= 100000000;
标签:COUNT,name,SUM,world,total,continent,select,population 来源: https://blog.csdn.net/Tracy785/article/details/89434336