> For the complete documentation index, see [llms.txt](https://dshub.gitbook.io/ds-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dshub.gitbook.io/ds-hub/sql/sql-practice/popular-websites-for-sql-practice/hackerrank/sql-basic/type-of-triangle.md). # Type of Triangle Advanced SELECT [Question Link](https://www.hackerrank.com/challenges/what-type-of-triangle/problem?isFullScreen=false) 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: * **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. * **Not A Triangle**: The given values of *A*, *B*, and *C* don't form a triangle. **Input Format** The **TRIANGLES** table is described as follows: ![](https://s3.amazonaws.com/hr-challenge-images/12887/1443815629-ac2a843fb7-1.png) Each row in the table denotes the lengths of each of a triangle's three sides. **Sample Input** ![](https://s3.amazonaws.com/hr-challenge-images/12887/1443815827-cbfc1ca12b-2.png) **Sample Output** ``` Isosceles Equilateral Scalene Not A Triangle ``` **Explanation** Values in the tuple ***(20,20,23)*** form an Isosceles triangle, because ***A=B***. Values in the tuple ***(20,20,20)*** form an Equilateral triangle, because ***A=B=C***. Values in the tuple ***(20,21,22)*** form a Scalene triangle, because ***A≠B≠C***. Values in the tuple ***(13,14,30)*** cannot form a triangle because the combined value of sides ***A*** and ***B*** is not larger than that of side ***C***. 
SELECT 
    CASE
        WHEN (A+B<=C OR B+C<=A OR C+A<=B) THEN 'Not A Triangle'
        WHEN (A=B AND B=C) THEN 'Equilateral'
        WHEN (A=B OR B=C OR C=A) THEN 'Isosceles'
        ELSE 'Scalene'
    END
FROM TRIANGLES