⭐ Type of Triangle

https://www.hackerrank.com/challenges/what-type-of-triangle

• Write a query identifying the type of each record in the TRIANGLES table using its three side lengths. Output one of the following statements for each record in the table:
• • Equilateral: It's a triangle with 3 sides of equal length.
    Isosceles: It's a triangle with 2 sides of equal length.
    Scalene: It's a triangle with 3 sides of differing lengths.
    Not A Triangle: The given values of A, B, and C don't form a triangle.

SELECT CASE
            WHEN A = B AND B = C THEN 'Equilateral'
            WHEN A + B <= C OR A + C <= B OR B + C <= A THEN 'Not A Triangle'
            WHEN A = B OR B = C OR A = C THEN 'Isosceles'
            ELSE 'Scalene'
       END
FROM triangles

Lesson & Learned

이렇게도 풀 수 있다.

SELECT CASE             
		WHEN A + B > C AND B + C > A AND A + C > B THEN
        	CASE 
             WHEN A = B AND B = C THEN 'Equilateral'
             WHEN A = B OR B = C OR A = C THEN 'Isosceles'
             ELSE 'Scalene'
        END
            ELSE 'Not A Triangle'
        END
FROM triangles