Closure Table

This is a mysql store procedure and trigger implementation of closure table in RDBMS about hierarchy data model.

Closure Table Node Paths

Query the subtree nodes

Features

• Automatically add new paths when you insert a new node

• Automatically update(DELETE old paths and INSERT new paths) paths when you update parent_id of a node. (This means move a node/subtree to a new parent)

• A store procedure that is used to select a whole subtree by a node_id (if the node_id has descendant)

Triggers

• trigger_add_paths

The trigger is execute when insert a node into prefix_nodes table, and call p_node_add to add update paths.

• prefix_node_move:

The trigger is execute when update the parent_id column of prefix_nodes table only if OLD.parent_id != NEW.parent_id

Store Procedures

• p_node_add(param_node_new_id INT UNSIGNED,param_node_parent_id INT UNSIGNED)

  Add new paths when insert a node to prefix_nodes table

• p_get_tree(node_id INT UNSIGNED)

  Get subtree by a node id

• p_node_move(node_old_parent_id INT UNSIGNED,node_new_parent_id INT UNSIGNED)

  Update paths when move a node to a new parent node

• p_node_hide(node_id INT UNSIGNED, is_deleted INT UNSIGNED)

  Hide or show nodes from subtree, explains as following:

  • Step 1. call p_get_tree(6) get the HARDWARE subtree,
  • Step 2. call p_node_hide(6, 0) to hide a subtree,
  • Step 3. call p_get_tree(6) get the HARDWARE subtree, when you get a subtree, it is not show in the result.
  • Step 4. call p_node_hide(6, 1) show HARDWARE subtree

MySQL Files

• ./mysql/tables.sql

  Create tables.

• ./mysql/sample_data.sql

  Some insert statements for testing

Postgresql Files

TODO::