Q4_e

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 C = A then 'Isosceles'
                    else 'Scalene'
                end
            else 'Not A Triangle' end
from triangles