Styjun

Why my solution of a problem on the study site is not accepted and showing "wrong answer"?

Here is the problem - https://www.hackerrank.com/challenges/the-pads/problem/ :

Generate the following two result sets:

1. Query an alphabetically ordered list of all names in OCCUPATIONS, immediately followed by the first letter of each profession as a parenthetical (i.e.: enclosed in parentheses). For example: AnActorName(A), ADoctorName(D), AProfessorName(P), and ASingerName(S).




2. Query the number of occurrences of each occupation in OCCUPATIONS. Sort the occurrences in ascending order, and output them in the following format:

There are a total of [occupation_count] [occupation]s.

where [occupation_count] is the number of occurrences of an occupation in OCCUPATIONS and [occupation] is the lowercase occupation name. If more than one Occupation has the same [occupation_count], they should be ordered alphabetically.

My query is:

SELECT 
 CAST(NAME, CASE 
 WHEN occupation = 'Actor' THEN '(A)' 
 WHEN occupation = 'Doctor' THEN '(D)' 
 WHEN occupation = 'Professor' THEN '(P)' 
 WHEN occupation = 'Singer' THEN '(S)' 
 END) 
FROM 
 occupations; 

and

SELECT 
 CASE 
 WHEN occupation = 'Actor' 
 THEN CONCAT('There are a total of ', COUNT(occupation), ' ', LOWER(occupation), 's.') 
 WHEN occupation = 'Doctor' 
 THEN CONCAT('There are a total of ', COUNT(occupation), ' ', LOWER(occupation), 's.') 
 WHEN occupation = 'Singer' 
 THEN CONCAT('There are a total of ', COUNT(occupation), ' ', LOWER(occupation), 's.') 
 WHEN occupation = 'Professor' 
 THEN CONCAT('There are a total of ', COUNT(occupation), ' ', LOWER(occupation), 's.') 
 END 
 FROM
 occupations 
 GROUP BY 
 occupation 
 ORDER BY 
 COUNT(occupation), occupation; 

The query has same output like in the example on HackerRank. What am I doing wrong?

Two issues:

• The solution should work for any occupation, not just for Actor, Doctor, Profession or Singer. The tests that have different occupation data will fail.


• The first result is not ordered as was requested

First query:

SELECT CONCAT(Name, '(', substr(Occupation, 1, 1), ')')
FROM Occupations
ORDER BY Name;

Your second query again expects a few static occupations but will return null when the occupation in the test data is not one of them. Don't use CASE here.

SELECT CONCAT('There are a total of ', COUNT(Occupation), ' ', LOWER(Occupation), 's.') 
FROM Occupations
GROUP BY Occupation 
ORDER BY COUNT(Occupation),
 Occupation;