[hackerrank] Weather Observation Station 4

[hackerrank] Prepare > SQL > Basic Select >  Weather Observation Station 4

 

[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:

where LAT_N is the northern latitude and LONG_W is the western longitude.

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 , because .

 

[MYSQL]

 

 

[ORCALE]

select count(*)-count(distinct(city))
from station;