Hierarchical data with SQL Query

Here is what SQL gives to avoid recursion in program.
You can get parents in tree like hierarchy.

WITH [ RECURSIVE ]  [ (  ) ]
AS (  )


The use of only the WITH clause (without the keyword RECURSIVE), is to
build a Common Table Expression (CTE). In a way CTE is a view build
especially for a query and used in one shot: each time we execute the
query. In one sense it can be called a "non persistent view".

A simple example for you.

SELECT COUNT(NEW_ID) AS NEW_NBR, NEW_FORUM
FROM   T_NEWS
GROUP  BY NEW_FORUM

WITH
  Q_COUNT_NEWS (NBR, FORUM)
  AS
    (
SELECT COUNT(NEW_ID), NEW_FORUM
     FROM   T_NEWS
     GROUP  BY NEW_FORUM),
  Q_MAX_COUNT_NEWS (NBR)
  AS (SELECT MAX(NBR)
      FROM   Q_COUNT_NEWS
)
SELECT T1.*
FROM   Q_COUNT_NEWS T1
      INNER JOIN Q_MAX_COUNT_NEWS T2
            ON T1.NBR = T2.NBR

With this query you can get output like.

ALL
|--SEA
|  |--SUBMARINE
|  |--BOAT
|--EARTH
|  |--CAR
|  |--TWO WHEELES
|  |  |--MOTORCYCLE
|  |  |--BYCYCLE
|  |--TRUCK
|--AIR
  |--ROCKET

So use this SQL advantage to lower the program overheads.
  |--PLANE