task: #608

Author: Ivanbyone

README.md

@@ -161,6 +161,7 @@ Useful for preparing for technical interviews and improving your SQL skills.
     - [570. Managers with at Least 5 Direct Reports](./leetcode/medium/570.%20Managers%20with%20at%20Least%205%20Direct%20Reports.sql)
     - [585. Investments in 2016](./leetcode/medium/585.%20Investments%20in%202016.sql)
     - [602. Friend Requests II: Who Has the Most Friends](./leetcode/medium/602.%20Friend%20Requests%20II:%20Who%20Has%20the%20Most%20Friends.sql)
+    - [608. Tree Node](./leetcode/medium/608.%20Tree%20Node.sql)
     - [626. Exchange Seats](./leetcode/medium/626.%20Exchange%20Seats.sql)
     - [1045. Customers Who Bought All Products](./leetcode/medium/1045.%20Customers%20Who%20Bought%20All%20Products.sql)
     - [1070. Product Sales Analysis III](./leetcode/medium/1070.%20Product%20Sales%20Analysis%203.sql)

leetcode/medium/608. Tree Node.sql

@@ -0,0 +1,38 @@
+/*
+Question 608. Tree Node
+Link: https://leetcode.com/problems/tree-node/description/?envType=problem-list-v2&envId=database
+
+Table: Tree
+
++-------------+------+
+| Column Name | Type |
++-------------+------+
+| id          | int  |
+| p_id        | int  |
++-------------+------+
+id is the column with unique values for this table.
+Each row of this table contains information about the id of a node and the id of its parent node in a tree.
+The given structure is always a valid tree.
+ 
+
+Each node in the tree can be one of three types:
+
+"Leaf": if the node is a leaf node.
+"Root": if the node is the root of the tree.
+"Inner": If the node is neither a leaf node nor a root node.
+Write a solution to report the type of each node in the tree.
+
+Return the result table in any order.
+*/
+
+SELECT
+    t.id,
+    (CASE
+        WHEN t.p_id IS NULL THEN 'Root'
+        WHEN t.id IN (
+            SELECT DISTINCT t1.p_id
+            FROM Tree AS t1
+        ) THEN 'Inner'
+        ELSE 'Leaf'
+    END) AS type --noqa: RF04
+FROM Tree AS t