working with permutations of a column values - sql

Question

I am trying from the below table
key val
A 10
B 20
C 30
D 40
to achieve the following result. Column label displays all combinations of key in alphabetical order. Column total displays the addition of the vals for the combination of keys.
label total
A 10
AB 30
ABC 60
ABCD 100
AC 40
AD 50
B 20
BC 50
BCD 90
BD 60
C 30
CD 70
D 40
while managed to get a query going, still not so convinced with it. Looking for better ways to get the same result set. thanks in advance.
with f (rn, key, val) as
(
select rownum, a.* from
(
select 'A' key, 10 val from dual
union all select 'B', 20 from dual
union all select 'C', 30 from dual
union all select 'D', 40 from dual
-- union all select 'E', 50 from dual
-- union all select 'F', 60 from dual
order by 1
) a
)
,
-- irn, ikey, ival: anchor rownum, key and val to remember the starting row
-- rn, key, val: for the current row in the recursion
-- r1: current label in the recursion
-- r2: combination of anchor key and the current row key in the recursion
-- total: addition of all values for keys in r1
rs(irn, ikey, ival, rn, key, val, r1, r2, total) as
(
select rn, key, val, rn, key, val, key, null, val from f
union all
select rs.irn, rs.ikey, rs.ival, f.rn, f.key, f.val, rs.r1 || f.key, rs.ikey || f.key, rs.total+f.val
from rs join f on (f.rn = rs.rn+1)
)
,
-- to add the additional rows required for the r2 col
-- when either r2 is not empty and not the same as r1 in rs
frs(irn, ikey, ival, rn, key, val, r1, r2, total) as
(
select * from rs
union all
select irn, ikey, ival, rn, key, val, r2, r2, ival+val
from frs
where r2 is not null and r1 != r2
)
select r1, total from frs
order by 1
;

Answer 1

Here is one way - using recursive subquery factoring, available since Oracle 11.2:
with
-- Begin test data
test_data ( key, val ) as (
select 'A', 10 from dual union all
select 'B', 20 from dual union all
select 'C', 30 from dual union all
select 'D', 40 from dual
),
-- End of test data (not part of the solution).
-- SQL query begins with the keyword "with" from above and continues below this line.
rec_cte ( label, total, last_symbol ) as (
select key, val, key -- anchor member
from test_data
union all
select r.label || t.key, r.total + t.val, t.key -- recursive member
from rec_cte r join test_data t on r.last_symbol < t.key
)
select label, total
from rec_cte
order by label -- if needed
;
Output:
LABEL TOTAL
----- -----
A 10
AB 30
ABC 60
ABCD 100
ABD 70
AC 40
ACD 80
AD 50
B 20
BC 50
BCD 90
BD 60
C 30
CD 70
D 40
15 rows selected.

Answer 2

You can use a PL/SQL block/Proceduere to achieve the same.
Assuming t_perm is your table, this proc will give you what you want. But currently it is displaying it on dbms_output. You can insert it in a table or display by a cursor etc. But this is the logic
create or replace procedure perm as
v_hold varchar2(20);
v_sum integer:=0;
cursor crs is select * from t_perm;
cursor crs1 is select * from t_perm;
begin
for rec in crs
loop
for rec1 in crs1
loop
if rec.key <= rec1.key then
v_hold:=v_hold||rec1.key;
v_sum:=v_sum+rec1.val;
dbms_output.put_line(v_hold||' '||v_sum);
end if;
end loop;
v_hold:='';
v_sum:=0;
end loop;
end;
Output
A 10
AB 30
ABC 60
ABCD 100
B 20
BC 50
BCD 90
C 30
CD 70
D 40