[Hacker Rank SQL 정복기] Advanced Select - ①

🥇 : Advanced Select > Type of Triangle

❓ Question

❗ Answer

SELECT
    CASE
    WHEN (a+b <= c OR b+c <= a OR c+a <= b) THEN 'Not A Triangle'
    WHEN a=b AND b=c THEN 'Equilateral'
    WHEN a=b OR b=c OR c=a THEN 'Isosceles'
    ELSE 'Scalene'
    END
FROM triangles;

📌 Discussion

• CASE WHEN (조건) THEN (대체값) ELSE 구문으로 호출
• 위의 조건부터 필터링이 걸리는 효과
• 마지막에 ELSE는 안써주어도 되나 END는 필수

🥇 : Advanced Select > The PADS

❓ Question

❗ Answer

SELECT CONCAT(name,'(', LEFT(occupation,1),')')
FROM occupations
ORDER BY name;

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

📌 Discussion

• text를 호출하기 위해서 CONCAT(가져올 text, 가져올 text, ... )로 작성
• GROUP BY로 occupation별로 묶어서 count