Type of triangle in MySQL

Question

Problem statement:

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:

• Not A Triangle: The given values of A, B, and C don't form a triangle.
• 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. 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
------------
A  B  C
20 20 23
20 20 20
20 21 22
13 14 30

Sample Output
-------------
Isosceles
Equilateral
Scalene
Not A Triangle

Attempt that did not work:

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"
        when A<>B and B<>C then "Scalene"

    end as triangles_type
    from TRIANGLES;

Answer 1

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'
    WHEN A <> B and B <> C THEN 'Scalene'
  END tuple
FROM TRIANGLES;

1. By using a case statement, check if a given input is a triangle or not.
2. If it is a triangle then check if all sides are same. If true the triangle type is 'Equilateral'.
3. If not, then check if any two sides are equal. If true, the triangle type is 'Isosceles'
4. In the case of not equal, any sides the triangle type is 'Scalene'. We can directly use ELSE also.