what many efficient/elegant proceed parse boring list tree?

assume have boring list stores an systematic tree hierarchy:

id   name         parentid   order
 1   'node 1'            0      10
 2   'node 1.1'          1      10
 3   'node 2'            0      20
 4   'node 1.1.1'        2      10
 5   'node 2.1'          3      10
 6   'node 1.2'          1      20

here's diagram, where have [id] name. bottom node 0 fictional.

                       [0] root
                          /    \ 
              [1] node 1          [3] node 2
              /       \                   \
    [2] node 1.1     [6] node 1.2      [5] node 2.1
          /          
 [4] node 1.1.1

what minimalistic proceed cost html (or text, matter) justly ordered, justly indented tree?

assume offer wholly have simple information structures (arrays hashmaps), imagination objects parent/children references, orm, framework, only your twin hands. list represented outcome set, accessed randomly.

pseudo formula plain english okay, definitely devising question.

bonus question: there essentially improved proceed store tree structure rdbms?

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edits additions

to answer commenter's ('s) question: bottom node necessary, since never going displayed anyway. parentid = 0 party demonstrate "these tip level". method buttress defines nodes same progenitor going sorted.

the "result set" i spoke graphic an array hashmaps (to stay terminology). instance meant already there. answers additional mile make first, nonetheless thats okay.

the tree arbitrarily deep. any node have n children. i accurately have "millions entries" tree mind, though.

don't mistake choice node controlling ('node 1.1.1') something rest on. nodes equally good called 'frank' 'bob', controlling structure implied, merely readable.

i have posted possess fortitude guys lift pieces.