[Hacker Rank] The Report

https://www.hackerrank.com/challenges/the-report/problem?isFullScreen=true 

The Report | HackerRank

 

You are given two tables: Students and Grades. Students contains three columns ID, Name and Marks.

Grades contains the following data:

Ketty gives Eve a task to generate a report containing three columns: Name, Grade and Mark. Ketty doesn't want the NAMES of those students who received a grade lower than 8. The report must be in descending order by grade -- i.e. higher grades are entered first. If there is more than one student with the same grade (8-10) assigned to them, order those particular students by their name alphabetically. Finally, if the grade is lower than 8, use "NULL" as their name and list them by their grades in descending order. If there is more than one student with the same grade (1-7) assigned to them, order those particular students by their marks in ascending order.

Write a query to help Eve.

Sample Input

Note

Print "NULL"  as the name if the grade is less than 8.

Explanation

Consider the following table with the grades assigned to the students:

So, the following students got 8, 9 or 10 grades:

• Maria (grade 10)
• Jane (grade 9)
• Julia (grade 9)
• Scarlet (grade 8)

---

[My Answer]

SELECT 
(CASE B.Grade>=8 WHEN TRUE THEN A.Name ELSE null END),
B.Grade,
A.Marks 
FROM STUDENTS A 
INNER JOIN 
GRADES B 
ON A.Marks BETWEEN Min_Mark AND Max_Mark 
ORDER BY B.Grade DESC, A.Name ,A.Marks ASC;

 

Join 뒤에 Between을 쓰는 방법을 잘 몰랐었다.

이게 간단하고, 예전에는 이런 상황이였으면 case when으로 하드코딩을 했을텐데, 찾아보니 더 between을 써주는 방식이 더 깔끔하다.