HackerRank SQL Solution - Advanced Select - 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.

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.

Sample Input:

Sample Output:

Isosceles
Equilateral
Scalene
Not A Triangle

Explanation:

• Values in the tuple (20,20,23) form an Isosceles triangle, because of A = B.
• Values in the tuple (20,20,20) form an Equilateral triangle, because of A = B = C.
• Values in the tuple (20,21,22) form a Scalene triangle, because of 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.

Solution:

/* Editor - MySQL */
SELECT 
CASE
    WHEN A+B>C AND B+C>A AND C+A>B THEN 
    CASE
        WHEN A=B AND B=C THEN "Equilateral"
        WHEN A=B OR B=C OR A=C THEN "Isosceles"
        WHEN A<>B AND B<>C AND C<>A  THEN "Scalene"
    END
ELSE "Not A Triangle"
END
FROM TRIANGLES

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