Hvordan skriver man involveret rekursiv underforespørgsel i sqlplus med flere tabeller for at spore noder?

I dit forenklede eksempel (som jeg begyndte at bruge dine rigtige tabelnavne, men det er de originale data) kan du få alle ruterne gennem flere switches med:

with rcte (rootsectionnumber, fromsectionnumber, tosectionnumber) as (
  select fromsectionnumber, fromsectionnumber, tosectionnumber
  from switchingdevice
  where normalswitchingdevicestate = 'CLOSED'
  union all
  select r.rootsectionnumber, sd.fromsectionnumber, sd.tosectionnumber
  from rcte r
  join switchingdevice sd on sd.fromsectionnumber = r.tosectionnumber
)
select rootsectionnumber, tosectionnumber from rcte;

ROOTSECTIONNUMBER TOSECTIONNUMBER
----------------- ---------------
               54             105
              105             106
              105             999
              999             700
               54             106
              105             500
               54             999
              105             700
               54             500
               54             700

hvoraf den ene har en ende-til-ende-rute fra sektion 54 til 700; og du kan derefter forbinde det med belastningsdefinitionen:

with rcte (rootsectionnumber, fromsectionnumber, tosectionnumber) as (
  select fromsectionnumber, fromsectionnumber, tosectionnumber
  from switchingdevice
  where normalswitchingdevicestate = 'CLOSED'
  union all
  select r.rootsectionnumber, sd.fromsectionnumber, sd.tosectionnumber
  from rcte r
  join switchingdevice sd on sd.fromsectionnumber = r.tosectionnumber
)
select ld.loadnumber, t.transformernumber
from loaddefinition ld
join rcte r on r.rootsectionnumber = ld.sectionnumber
join transformer t on t.tosectionnumber = r.tosectionnumber
where ld.loadnumber = 100;

LOADNUMBER TRANSFORMERNUMBER
---------- -----------------
       100              5000

Eller hvis du skal inkludere busnumber i logikken (baseret på et kort kig på din større forespørgsel...):

with rcte (rootsectionnumber, busnumber, fromsectionnumber, tosectionnumber) as (
  select fromsectionnumber, busnumber, fromsectionnumber, tosectionnumber
  from switchingdevice
  where normalswitchingdevicestate = 'CLOSED'
  union all
  select r.rootsectionnumber, r.busnumber, sd.fromsectionnumber, sd.tosectionnumber
  from rcte r
  join switchingdevice sd on sd.fromsectionnumber = r.tosectionnumber
  and sd.busnumber = r.busnumber
)
select ld.loadnumber, t.transformernumber
from loaddefinition ld
join rcte r on r.rootsectionnumber = ld.sectionnumber
and r.busnumber = ld.busnumber
join transformer t on t.tosectionnumber = r.tosectionnumber
and t.tobusnumber = r.busnumber
where ld.loadnumber = 100;

LOADNUMBER TRANSFORMERNUMBER
---------- -----------------
       100              5000

db<>fiddle

Tilføjelse af dine andre tabeller vil naturligvis komplicere tingene en smule, men det er ikke helt klart, hvordan de alle er relateret.