Given a table tree, id is identifier of the tree node and p_id is its parent node's id.
+----+------+ | id | p_id | +----+------+ | 1 | null | | 2 | 1 | | 3 | 1 | | 4 | 2 | | 5 | 2 | +----+------+
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 query to print the node id and the type of the node. Sort your output by the node id. The result for the above sample is:
+----+------+ | id | Type | +----+------+ | 1 | Root | | 2 | Inner| | 3 | Leaf | | 4 | Leaf | | 5 | Leaf | +----+------+
Explanation
- Node '1' is root node, because its parent node is NULL and it has child node '2' and '3'.
- Node '2' is inner node, because it has parent node '1' and child node '4' and '5'.
- Node '3', '4' and '5' is Leaf node, because they have parent node and they don't have child node.
- And here is the image of the sample tree as below:
1 / \ 2 3 / \ 4 5Note
If there is only one node on the tree, you only need to output its root attributes.
[Database]