È un po' disordinato, ma potresti farlo in semplice SQL, iniziando con una query gerarchica per ottenere le stringhe concatenate:
select keyvalue, fromtable, colsavailable, rnk,
ltrim(sys_connect_by_path(colsavailable, '||''|''||'), '||''|''||') as path
from ordercols_forview
start with rnk = 1
connect by keyvalue = prior keyvalue
and rnk = prior rnk + 1
and prior dbms_random.value is not null
order by keyvalue, fromtable, colsavailable, rnk;
KEYVALUE FR COLS RNK PATH
---------- -- ---- ---------- --------------------------------------------------
1 A1 NUM1 1 NUM1
1 A1 NUM2 2 NUM1||'|'||NUM2
1 A1 NUM3 3 NUM1||'|'||NUM2||'|'||NUM3
2 B1 NUM1 1 NUM1
2 B1 NUM2 2 NUM1||'|'||NUM2
2 B1 NUM3 3 NUM1||'|'||NUM2||'|'||NUM3
2 B1 NUM4 4 NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4
3 C1 NUM1 1 NUM1
3 C1 NUM2 2 NUM1||'|'||NUM2
3 C1 NUM3 3 NUM1||'|'||NUM2||'|'||NUM3
3 C1 NUM4 4 NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4
3 C1 NUM5 5 NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4||'|'||NUM5
Ho presupposto che la tua tabella abbia davvero un'altra colonna che non hai mostrato che fornisce la posizione della colonna. In caso contrario, puoi generarlo in qualche modo, magari in base a column_id per la colonna della tabella di base, in ordine alfabetico o altro. Hai solo bisogno di una sequenza numerica contigua per la clausola di connessione.
Puoi quindi utilizzare due unioni per ottenere le parti di testo per quelle colonne e valori di percorso (poiché devono essere righe separate nella tabella finale), più altre extra per SELECT ... e FROM ... linee. Ognuno di questi ha bisogno di un altro numero di rango generato. Quelli possono essere generati dalla classifica nel CTE:
with ordercols_forview_cte as (
select keyvalue, fromtable, colsavailable, rnk,
ltrim(sys_connect_by_path(colsavailable, '||''|''||'), '||''|''||') as path
from ordercols_forview
start with rnk = 1
connect by keyvalue = prior keyvalue
and rnk = prior rnk + 1
and prior dbms_random.value is not null
)
select 'CREATE OR REPLACE VIEW ' || s.view_to_be_created || ' AS SELECT ' as text,
s.view_to_be_created, 1 as rnk
from seeding_table s
union all
select 'KEYVALUE,' as text,
s.view_to_be_created, 2 as rnk
from seeding_table s
union all
select o.path || ' AS KEY' || o.rnk
|| case when o.rnk < s.noofcols then ',' end,
s.view_to_be_created, (o.rnk * 2) + 1 as rnk
from seeding_table s
join ordercols_forview_cte o on o.keyvalue = s.keyvalue
union all
select o.colsavailable || ' AS NO' || o.rnk
|| case when o.rnk < s.noofcols then ',' end as text,
s.view_to_be_created, (o.rnk * 2) + 2 as rnk
from seeding_table s
join ordercols_forview_cte o on o.keyvalue = s.keyvalue
union all
select 'FROM ' || o.fromtable || ';' as text,
s.view_to_be_created, (s.noofcols * 2) + 3 as rnk
from seeding_table s
join ordercols_forview_cte o on o.keyvalue = s.keyvalue
where o.rnk = s.noofcols
order by view_to_be_created, rnk;
Che con i tuoi dati di partenza genera:
TEXT V RNK
------------------------------------------------------------ - ----------
CREATE OR REPLACE VIEW A AS SELECT A 1
KEYVALUE, A 2
NUM1 AS KEY1, A 3
NUM1 AS NO1, A 4
NUM1||'|'||NUM2 AS KEY2, A 5
NUM2 AS NO2, A 6
NUM1||'|'||NUM2||'|'||NUM3 AS KEY3 A 7
NUM3 AS NO3 A 8
FROM A1; A 9
CREATE OR REPLACE VIEW B AS SELECT B 1
KEYVALUE, B 2
NUM1 AS KEY1, B 3
NUM1 AS NO1, B 4
NUM1||'|'||NUM2 AS KEY2, B 5
NUM2 AS NO2, B 6
NUM1||'|'||NUM2||'|'||NUM3 AS KEY3, B 7
NUM3 AS NO3, B 8
NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4 AS KEY4 B 9
NUM4 AS NO4 B 10
FROM B1; B 11
CREATE OR REPLACE VIEW C AS SELECT C 1
KEYVALUE, C 2
NUM1 AS KEY1, C 3
NUM1 AS NO1, C 4
NUM1||'|'||NUM2 AS KEY2, C 5
NUM2 AS NO2, C 6
NUM1||'|'||NUM2||'|'||NUM3 AS KEY3, C 7
NUM3 AS NO3, C 8
NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4 AS KEY4, C 9
NUM4 AS NO4, C 10
NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4||'|'||NUM5 AS KEY5 C 11
NUM5 AS NO5 C 12
FROM C1; C 13
Potresti variarlo un po', avendo un altro CTE con il join tra seeding_table e ordercols_forview_cte e usandolo per il sindacato. Puoi anche ottenere i percorsi da un CTE ricorsivo (da Oracle 11g):
with r (keyvalue, fromtable, colsavailable, rnk, path) as (
select keyvalue, fromtable, colsavailable, rnk, colsavailable
from ordercols_forview
where rnk = 1
union all
select ocfv.keyvalue, ocfv.fromtable, ocfv.colsavailable, ocfv.rnk,
r.path || q'[||'|'||]' || ocfv.colsavailable
from r
join ordercols_forview ocfv
on ocfv.keyvalue = r.keyvalue
and ocfv.fromtable = r.fromtable
and ocfv.rnk = r.rnk + 1
)
select * from r;
E puoi quindi usarlo invece; questo fa il join tra quel CTE ricorsivo e la tabella di seeding in un altro CTE come menzionato sopra, ma potresti semplicemente sostituire il CTE della query gerarchica con quello ricorsivo:
with r (keyvalue, fromtable, colsavailable, rnk, path) as (
select keyvalue, fromtable, colsavailable, rnk, colsavailable
from ordercols_forview
where rnk = 1
union all
select ocfv.keyvalue, ocfv.fromtable, ocfv.colsavailable, ocfv.rnk,
r.path || q'[||'|'||]' || ocfv.colsavailable
from r
join ordercols_forview ocfv
on ocfv.keyvalue = r.keyvalue
and ocfv.fromtable = r.fromtable
and ocfv.rnk = r.rnk + 1
),
combined_cte as (
select s.keyvalue, s.view_to_be_created, s.noofcols,
r.fromtable, r.colsavailable, r.rnk, r.path
from seeding_table s
join r on r.keyvalue = s.keyvalue
)
select 'CREATE OR REPLACE VIEW ' || c.view_to_be_created || ' AS SELECT ' as text,
c.view_to_be_created, c.rnk
from combined_cte c
where c.rnk = 1
union all
select 'KEYVALUE,' as text,
c.view_to_be_created, c.rnk + 1 as rnk
from combined_cte c
where c.rnk = 1
union all
select c.path || ' AS KEY' || c.rnk
|| case when c.rnk < c.noofcols then ',' end,
c.view_to_be_created, (c.rnk * 2) + 1 as rnk
from combined_cte c
union all
select c.colsavailable || ' AS NO' || c.rnk
|| case when c.rnk < c.noofcols then ',' end as text,
c.view_to_be_created, (c.rnk * 2) + 2 as rnk
from combined_cte c
union all
select 'FROM ' || c.fromtable || ';' as text,
c.view_to_be_created, (c.noofcols * 2) + 3 as rnk
from combined_cte c
where c.rnk = c.noofcols
order by view_to_be_created, rnk;
Che ottiene lo stesso risultato:
TEXT V RNK
------------------------------------------------------------ - ----------
CREATE OR REPLACE VIEW A AS SELECT A 1
KEYVALUE, A 2
NUM1 AS KEY1, A 3
NUM1 AS NO1, A 4
NUM1||'|'||NUM2 AS KEY2, A 5
NUM2 AS NO2, A 6
...
NUM1||'|'||NUM2||'|'||NUM3 AS KEY3, C 7
NUM3 AS NO3, C 8
NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4 AS KEY4, C 9
NUM4 AS NO4, C 10
NUM1||'|'||NUM2||'|'||NUM3||'|'||NUM4||'|'||NUM5 AS KEY5 C 11
NUM5 AS NO5 C 12
FROM C1; C 13
