[HackerRank/Basic Join] The Report

https://www.hackerrank.com/challenges/the-report/problem 

The Report | HackerRank

 

문제

 

풀이

 

SELECT IF(G.Grade >= 8, S.Name, "NULL"), G.Grade, S.Marks 
FROM Students AS S
INNER JOIN Grades AS G
ON S.Marks >= G.Min_Mark AND S.Marks <= G.Max_Mark
ORDER BY G.Grade DESC, S.Name ASC, S.Marks ASC

 

• MYSQL IF문
  IF ( 조건문, 참일때 값, 거짓일때 값) FROM TABLE
• MYSQL CASE문
  CASE
      WHEN 조건1 THEN 반환값1
      WHEN 조건2 THEN 반환값2
      ELSE 충족하는 조건이 없을 때의 반환값
  END
• MYSQL IFNULL문
  IFNULL ( 값1, 값2 )   # 값1이 NULL이면 값2를 반환, NULL이 아니면 값1을 반환

 

다른 풀이

SELECT IF(G.Grade >= 8, S.Name, "NULL"), G.Grade, S.Marks 
FROM Students AS S
INNER JOIN Grades AS G
ON S.Marks BETWEEN G.Min_Mark AND G.Max_Mark
ORDER BY G.Grade DESC, S.Name ASC, S.Marks ASC

• X BETWEEN A AND B
  A <= X <= B