Question

I’ve got a table bbc with the following columns:

name (refers to a name of a country within a particular region of the world)

region (continent of the world)

population (population of the country in the name name field)
The question I’m trying to answer:

The question is as follows:
“Some countries have populations more than three times that of any of their neighbours (in the same region). Give the countries and regions.”

I was thinking the answer might be something like:

SELECT a.name, a.region FROM bbc AS a
WHERE a.region IN
     (
        SELECT b.region FROM bbc AS b 
        GROUP By b.region 
        HAVING MIN(b.population) < 3*b.population)

But honestly, I lose it at that last line… I have no idea how I would find counteries that have more than three times that of any of their neighbours in the same region! Quite tough. O_o

Any and all help would be appreciated.

Answer 1

select
   a.name, a.region
from bbc as a
where 
    a.population >
    (
        select 3*max(b.population)
        from bbc as b
        where b.region = a.region and b.name <> a.name
    )