Het is een beetje rommelig, maar je zou het in gewone SQL kunnen doen, te beginnen met een hiërarchische query om de aaneengeschakelde strings te krijgen:
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
Ik ben ervan uitgegaan dat je tabel echt een andere kolom heeft die je niet hebt getoond en die de kolompositie geeft. Als dat niet het geval is, kunt u dat op de een of andere manier genereren - misschien op basis van column_id voor de basistabelkolom, alfabetisch of wat dan ook. Je hebt alleen een aaneengesloten nummerreeks nodig voor de connect-by-clausule.
Je kunt dan twee vakbonden gebruiken om de tekstdelen voor die kolom- en padwaarden te krijgen (omdat ze aparte rijen in je uiteindelijke tabel moeten zijn), plus extra voor de SELECT ... en FROM ... lijnen. Elk van deze heeft een ander gegenereerd rangnummer nodig. Die kunnen worden gegenereerd uit de rangschikking in de 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;
Die met uw startgegevens genereert:
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
Je zou het een beetje kunnen variëren, met een andere CTE met de join tussen seeding_table en ordercols_forview_cte en dat gebruiken voor de vakbond. U kunt de paden ook uit een recursieve CTE halen (van 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;
En kan dat dan in plaats daarvan gebruiken; dit doet de verbinding tussen die recursieve CTE en de seeding-tabel in een andere CTE zoals hierboven vermeld, maar je kunt de hiërarchische query-CTE gewoon vervangen door de recursieve:
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;
Wat hetzelfde resultaat oplevert:
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