This question needs to be rewritten for clarity. "the possible minimum value" is completely unclear and doesn't give any idea as to the scope of the question. The shortest city name in the table is my best guess, but it shouldn't be a guessing game.

In fact, this question is so unclear and contrived I really think it should be removed.

Please instead of compiler just saying wrong answer as a reason it should show us the expected output, it gives us more clues when the question isn't explanatory enough

Here is Oracle solution from my HackerrankPractice repository:

SELECT *
FROM
    (SELECT CITY, LENGTH(CITY)
    FROM STATION
    ORDER BY LENGTH(CITY), CITY)
WHERE ROWNUM = 1
UNION
SELECT *
FROM
    (SELECT CITY, LENGTH(CITY)
    FROM STATION
    ORDER BY LENGTH(CITY) DESC, CITY)
WHERE ROWNUM = 1;

Feel free to ask if you have any questions :)

Answer in MS SQL SERVER:

SELECT TOP 1 CITY, LEN(CITY) FROM STATION ORDER BY LEN(CITY),CITY; SELECT TOP 1 CITY, LEN(CITY) FROM STATION ORDER BY LEN(CITY) DESC,CITY;

My SQL Version:

select city, length(city) from station
order by length(city),city asc
limit 1;
select city, length(city) from station
order by length(city) desc
limit 1;