[MySQL/HackerRank] Weather Observation Station 4

https://www.hackerrank.com/challenges/weather-observation-station-4/problem?isFullScreen=true 

Weather Observation Station 4 | HackerRank

문제

Find the difference between the total number of CITY entries in the table and the number of distinct CITY entries in the table.
The STATION table is described as follows:

Code

SELECT COUNT(CITY) - COUNT(DISTINCT(CITY))
FROM STATION;