[SQL] 해커랭크 Type of Triangle

문제

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  sides of equal length.
Isosceles: It's a triangle with  sides of equal length.
Scalene: It's a triangle with  sides of differing lengths.
Not A Triangle: The given values of A, B, and C don't form a triangle.

 

Input Format
The TRIANGLES table is described as follows:

Each row in the table denotes the lengths of each of a triangle's three sides.

 

https://www.hackerrank.com/challenges/what-type-of-triangle/problem?isFullScreen=true

Type of Triangle | HackerRank

예시

Sample Input

Sample Output

Isosceles
Equilateral
Scalene
Not A Triangle

Explanation
Values in the tuple (20, 20, 23) form an Isosceles triangle, because A = B.
Values in the tuple (20, 20, 20) form an Equilateral triangle, because A = B = C.

Values in the tuple (20, 21, 22) form a Scalene triangle, because A <> B <> C.
Values in the tuple (13, 14, 30) cannot form a triangle because the combined value of sides  A and  B is not larger than that of side C.

문제 풀이

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

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