The simplest way to store a tree structure into a database is obviously the table structure in which each record represents a node, and where a column is used to specify the key of the parent node.
This is by far the most convenient way for tree operation handling (insert, delete a node, etc.).
The tree traversal is very easy and is done with a simple recursive micro-function.
The downside to this advantage (and yes, it is well known: each advantage generates 1 or n disadvantages.)
lies in the fact that the recursive traversal requires the processing of an SQL query on each function call.
Fortunately, there is an enhanced database structure that allows fast tree traversal:
A single SQL query does the job!