I am trying to display hierarchical data with MySQL (MariaDB) query, to show relationships,( like list of recipes, corporate org chart or program hierarchy). I can do some manipulation in PHP if required. In DB2 I can use CONNECT_BY_ROOT and CONNECT BY PRIOR to make these relationships, but MySQL does not support this vocabulary.

Example: Input

   Parent Child
    A        D
    B        E
    B        G
    E        H 

Output

1.     A
1.1      D
  
2.     B
2.1      E
2.1.1      H
2.2      G

The closest I get with MySQL is by using a Common Table Expression:

WITH RECURSIVE hierarchy_cte AS (
    -- Anchor member: start with the root parent
    SELECT WHPNAM  as parent,
           WHFNAM  as child
    FROM rf_pgm_ref
    WHERE WHPNAM = 'ADDRESSR'  -- Starting parent

    UNION ALL

    SELECT 
           h.WHPNAM    as parent,
           h.WHFNAM    as child
        FROM rf_pgm_ref h
    INNER JOIN hierarchy_cte cte ON h.WHPNAM = cte.child
)
SELECT DISTINCT   parent, child
FROM hierarchy_cte
ORDER BY parent, child;