SQLZOO(SUM and COUNT)Writeup

1.

SELECT SUM(population)
FROM world

2.

select DISTINCT(continent) from world

3.

select sum(gdp) from world where continent ='Africa'

4.

select count(name) from world where area>1000000

5.

select sum(population) from world where name in ('France','Germany','Spain')

6.

select continent,count(name) from world group by continent

7.

select continent,count(name) from world where population>= 10000000 group by continent

8.

select continent from world group by continent having sum(population)>=100000000

这里不能使用where语句，因为where语句不能与group by 一起使用。