[SQL문제풀기] Basic Select 8~

문제8 - Weather Observation Station 1

Weather Observation Station 1 | HackerRank

Write a query to print the CITY and STATE for each attribute in the STATION table.

https://www.hackerrank.com/challenges/weather-observation-station-1/problem?isFullScreen=true

MySQL, Oracle, DB2, MS SQL Server

select city, state from station;

문제9 - Weather Observation Station 3

Weather Observation Station 3 | HackerRank

Query a list of unique CITY names with even ID numbers.

https://www.hackerrank.com/challenges/weather-observation-station-3/problem?isFullScreen=true

MySQL, MS SQL Server

select distinct city from station where id % 2 = 0;

Oracle, DB2

select distinct city from station where mod(id,2)=0;

문제10 - Weather Observation Station 4

Weather Observation Station 4 | HackerRank

Find the number of duplicate CITY names in STATION.

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

MySQL,Oracle, DB2, MS SQL Server

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