# HackerRank: [SQL Advanced Select] (4/5) BINARY TREE NODES | case, when, if, sub-query in SQL

I started studying SQL from a very famous site - HackerRank. Here I will try to provide multiple approaches & solutions to the same problem. It will help you learn and understand SQL in a better way.

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**SQL Problem Statement:**

You are given a table, BST, containing two columns: N and P, where N represents the value of a node in Binary Tree, and P is the parent of N.

Write a query to find the node type of Binary Tree ordered by the value of the node. Output one of the following for each node:

**Root:**If node is root node.**Leaf:**If node is leaf node.**Inner:**If node is neither root nor leaf node.

**Input Format:**

The **BST **table is described as follows:

BST_Columns |

**Sample Input:**

The

**BST**table contains the following records:**Sample Output:**

**Explanation:**

The Binary Tree below illustrates the sample:

**Solution-1: Using CASE WHEN Statement (MySQL Query):**

**NOTE:**

- Parent for
**Root**Node is**Null**. - Any node which is the parent node of other nodes is an
**Inner**node - All remaining nodes are
**Leaf**nodes.

**Solution-2: Using IF Statement (MySQL Query):**

**NOTE:** - Parent for
**Root **Node is **Null**. - Any node which is the parent node of other nodes is an
**Inner **node - All remaining nodes are
**Leaf** nodes.

**NOTE:**

- Parent for
**Root**Node is**Null**. - Any node which is the parent node of other nodes is an
**Inner**node - All remaining nodes are
**Leaf**nodes.

**Sample Output:**

--------------------------------------------------------------------------------

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**-Akshay P Daga**

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