text: /*
  Difficulty: Medium
  
  https://www.hackerrank.com/challenges/weather-observation-station-7/problem 
  
  Query the list of CITY names ending with vowels (a, e, i, o, u) from STATION. Your result cannot contain duplicates.
  
  
  The STATION table is described as follows:
  +--------+--------------+
  | Field  |     Type     |
  +--------+--------------+
  | ID     | NUMBER       |
  | CITY   | VARCHAR2(21) |
  | STATE  | VARCHAR2(2)  |
  | LAT_N  | NUMBER       |
  | LONG_W | NUMBER       |
  +--------+--------------+
  where LAT_N is the northern latitude and LONG_W is the western longitude.
  */
  
  select distinct(city) 
  from station 
  where upper(substr(city,-1,1)) in ('A','E','I','O','U');