How to find Type of triangle(length of three sides are given) using nested case in mysql?

Question

What Is wrobg in this MySQL query? It is showing syntax error.

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

Answer 1

You have to add also a then for that purpose

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