Det er lidt rodet, men du kan gøre det i almindelig SQL, startende med en hierarkisk forespørgsel for at få de sammenkædede strenge:
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
Jeg går ud fra, at din tabel virkelig har en anden kolonne, du ikke har vist, som giver kolonnepositionen. Hvis ikke kan du generere det på en eller anden måde - måske baseret på column_id for basistabelkolonnen, alfabetisk eller hvad som helst. Du skal blot bruge en sammenhængende nummersekvens til connect-by-sætningen.
Du kan derefter bruge to fagforeninger til at få tekstdelene for disse kolonne- og stiværdier (da de skal være separate rækker i din endelige tabel), plus ekstra for SELECT ... og FROM ... linjer. Hver af disse har brug for et andet genereret rangnummer. Disse kan genereres fra rangeringen i 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;
Som med dine startdata genererer:
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
Du kan variere det lidt ved at have en anden CTE med joinforbindelsen mellem seeding_table og ordercols_forview_cte og bruge det til fagforeningen. Du kan også få stierne fra en rekursiv CTE (fra 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;
Og kan så bruge det i stedet for; dette forbinder den rekursive CTE og seedningstabellen i en anden CTE som nævnt ovenfor, men du kan bare erstatte den hierarkiske forespørgsel CTE med den rekursive:
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;
Hvilket får samme resultat:
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