SELECT
    B1.N,
    CASE
        WHEN B1.P IS NULL THEN "Root"
        WHEN NOT EXISTS (SELECT 1 FROM BST B2 WHERE B2.P = B1.N) THEN 'Leaf'
        ELSE "Inner"
    END AS NodeType
FROM 
    BST B1 
ORDER  
	BY B1.N;

Explanation: For leaf Node - We know that leaf node is parent to none of the node. The condition will determine whether a node B1.N is not a parent to any other node. If there is no row in the table where B2.P (parent column) equals B1.N (current node), then the current node is considered a Leaf.

SELECT 1 FROM BST B2 WHERE B2.P = B1.N looks for any child nodes where B1.N appears as a parent.

NOT EXISTS checks if there is no match for a given condition. Example: For N=1 Go to B2 and check if - B2.P = 1 -> Does any row in the table have P = 1? No such row exists. Hence, 1 is a Leaf.

If no match exists, the node has no children and is therefore a Leaf.

ORDER BY B1.N;