https://sqlzoo.net/wiki/SUM_and_COUNT
SUM and COUNT - SQLZOO
World Country Profile: Aggregate functions This tutorial is about aggregate functions such as COUNT, SUM and AVG. An aggregate function takes many values and delivers just one value. For example the function SUM would aggregate the values 2, 4 and 5 to del
sqlzoo.net
SUM and COUNT
--no1
select sum(population)
from world
--no2
select distinct continent from world
--no3
select sum(gdp)
from world
where continent = 'Africa'
--no4
select count(name)
from world
where area >= 1000000
--no5
select sum(population)
from world
where name in ('france', 'germany', 'spain')
--no6
select continent, count(name)
from world
group by continent
--no7
select continent, count(name)
from world
where population >= 10000000
group by continent
--no8
select continent from world
group by continent having sum(population) >= 100000000select distinct continent
from world x
where 100000000 <=
(select sum(population) from world y where x.continent = y.continent)