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:

Not A Triangle: The given values of A, B, and C don't form a triangle.
Equilateral: It's a triangle with 33 sides of equal length.
Isosceles: It's a triangle with 22 sides of equal length.
Scalene: It's a triangle with 33 sides of differing lengths.

select case 
    when A+B<=C then 'Not A Triangle' 
    when B+C<=A then 'Not A Triangle' 
    when C+A<=B then 'Not A Triangle' 
    when A=B then 
    case 
        when B=C then 'Equilateral' else 'Isosceles' 
    end 
    when B=C then 'Isosceles' 
    when A=C then 'Isosceles' else 'Scalene' end from TRIANGLES ;