Hackerrank - Weather Observation Station 4

Problem Statement
A description of the problem can be found on Hackerrank.

Solution
In a subselect selects count of all cities and unique cities and then substract these numbers.

I created solution in:

All solutions are also available on my GitHub.

SQL

select num - num_uniq
from (
    select count(city) as num, count(distinct city) as num_uniq 
    from station
);

select num - num_uniq

from (

select count(city) as num, count(distinct city) as num_uniq

from station

);

Pavol Pidanič