How to retrieve parents node by level in a tree

Objective

In a tree, from a node, retrieve the node's parent in the level indicated.

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Execution Steps

There are two database functions:

• function AD_GET_NODE_TREE_BYLEVEL

input params: ad_tree_id (VARCHAR(32)), node_id (VARCHAR(32)), level (NUMERIC)
output: node (VARCHAR(32))
This function returns one parent of the node. This parent is in the level indicated, where the level 0 is the first node of tree, in level 1 are the sons of this first node, etc...

• function AD_GET_LEVEL_NODE_TREE

input params: ad_tree_id (VARCHAR(32)), node_id (VARCHAR(32))
output: level (NUMERIC)
Returns the level of the node in the tree, where the level 0 is the first node of tree, in level 1 are the sons of this first node, etc...

• Example

The projects can be managed in a tree. So, you can group the projects in differents levels, allowing obtain info by level In this case, the nodes in first level are the main projects, and the projects in second level, are the secundary projects. The normal projects (leaf nodes) belong to a main project and a secundary project. The revenues and expenses are reported to the normal project (leaf nodes), and you can obtain information in the level of parent nodes. One example is represented in picture.

tree T: File:TreeFunctions.jpg

AD_GET_NODE_TREE_BYLEVEL ('T', 'E', 1) -> 'C'
AD_GET_NODE_TREE_BYLEVEL ('T', 'E', 0) -> 'A'
AD_GET_LEVEL_NODE_TREE ('T', 'B') -> 1
AD_GET_LEVEL_NODE_TREE ('T', 'D') -> 2

Sometimes, it is interesting to know what is the main and secundary project of a project.

Result

The functions return the ID of parent node in level indicated, and the level of the node in the tree.