hackerrank Weather Observation Station 4

Q: Find the difference between the total number of CITY entries in the table and the number of distinct CITY entries in the table.
For example, if there are three records in the table with CITY values 'New York', 'New York', 'Bengalaru', there are 2 different city names: 'New York' and 'Bengalaru'. The query returns 1 ( hint : total number of records - number of unique city names)

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

중복값을 제거할때 distinct를 적어둔다.