09 - Weather Observation Station 4.sql

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--       Information
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-- Direct Link: https://www.hackerrank.com/challenges/weather-observation-station-4/problem
-- Difficulty: Easy
-- Max Score: 10
-- DBMS: mySQL

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

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--       Explanation
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-- DISTINCT() used to avoid duplication
-- COUNT() used to return the number of rows in a table