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