Oracle grouping/changing rows to columns - sql

Question

I have the following table named foo:
ID | KEY | VAL
----------------
1 | 47 | 97
2 | 47 | 98
3 | 47 | 99
4 | 48 | 100
5 | 48 | 101
6 | 49 | 102
I want to run a select query and have the results show like this
UNIQUE_ID | KEY | ID1 | VAL1 | ID2 | VAL2 | ID3 | VAL3
--------------------------------------------------------------
47_1:97_2:98_3:99| 47 | 1 | 97 | 2 | 98 | 3 | 99
48_4:100_5:101 | 48 | 4 | 100 | 5 | 101 | |
49_6:102 | 49 | 6 | 102 | | | |
So, basically all rows with the same KEY get collapsed into 1 row. There can be anywhere from 1-3 rows per KEY value
Is there a way to do this in a sql query (without writing a stored procedure or scripts)?
If not, I could also work with the less desirable choice of
UNIQUE_ID | KEY | IDS | VALS
--------------------------------------------------------------
47_1:97_2:98_3:99| 47 | 1,2,3 | 97,98,99
48_4:100_5:101 | 48 | 4,5 | 100, 101
49_6:102 | 49 | 6 | 102
Thanks!
UPDATE:
Unfortunately my real-world problem seems to be much more difficult than this example, and I'm having trouble getting either example to work :( My query is over 120 lines so it's not very easy to post. It kind of looks like:
with v_table as (select ...),
v_table2 as (select foo from v_table where...),
v_table3 as (select foo from v_table where ...),
...
v_table23 as (select foo from v_table where ...)
select distinct (...) as "UniqueID", myKey, myVal, otherCol1, ..., otherCol18
from tbl1 inner join tbl2 on...
...
inner join tbl15 on ...
If I try any of the methods below it seems that I cannot do group-bys correctly because of all the other data being returned.
Ex:
with v_table as (select ...),
v_table2 as (select foo from v_table where...),
v_table3 as (select foo from v_table where ...),
...
v_table23 as (select foo from v_table where ...)
select "Unique ID",
myKey, max(decode(id_col,1,id_col)) as id_1, max(decode(id_col,1,myVal)) as val_1,
max(decode(id_col,2,id_col)) as id_2,max(decode(id_col,2,myVal)) as val_2,
max(decode(id_col,3,id_col)) as id_3,max(decode(id_col,3,myVal)) as val_3
from (
select distinct (...) as "UniqueID", myKey, row_number() over (partition by myKey order by id) as id_col, id, myVal, otherCol1, ..., otherCol18
from tbl1 inner join tbl2 on...
...
inner join tbl15 on ...
) group by myKey;
Gives me the error: ORA-00979: not a GROUP BY expression
This is because I am selecting the UniqueID from the inner select. I will need to do this as well as select other columns from the inner table.
Any help would be appreciated!

Answer 1

Take a look ath this article about Listagg function, this will help you getting the comma separated results, it works only in the 11g version.

Answer 2

You may try this
select key,
max(decode(id_col,1,id_col)) as id_1,max(decode(id_col,1,val)) as val_1,
max(decode(id_col,2,id_col)) as id_2,max(decode(id_col,2,val)) as val_2,
max(decode(id_col,3,id_col)) as id_3,max(decode(id_col,3,val)) as val_3
from (
select key, row_number() over (partition by key order by id) as id_col,id,val
from your_table
)
group by key

Answer 3

As #O.D. suggests, you can generate the less desirable version with LISTAGG, for example (using a CTE to generate your sample data):
with foo as (
select 1 as id, 47 as key, 97 as val from dual
union select 2,47,98 from dual
union select 3,47,99 from dual
union select 4,48,100 from dual
union select 5,48,101 from dual
union select 6,49,102 from dual
)
select key ||'_'|| listagg(id ||':' ||val, '_')
within group (order by id) as unique_id,
key,
listagg(id, ',') within group (order by id) as ids,
listagg(val, ',') within group (order by id) as vals
from foo
group by key
order by key;
UNIQUE_ID KEY IDS VALS
----------------- ---- -------------------- --------------------
47_1:97_2:98_3:99 47 1,2,3 97,98,99
48_4:100_5:101 48 4,5 100,101
49_6:102 49 6 102
With a bit more manipulation you can get your preferred results:
with foo as (
select 1 as id, 47 as key, 97 as val from dual
union select 2,47,98 from dual
union select 3,47,99 from dual
union select 4,48,100 from dual
union select 5,48,101 from dual
union select 6,49,102 from dual
)
select unique_id, key,
max(id1) as id1, max(val1) as val1,
max(id2) as id2, max(val2) as val2,
max(id3) as id3, max(val3) as val3
from (
select unique_id,key,
case when r = 1 then id end as id1, case when r = 1 then val end as val1,
case when r = 2 then id end as id2, case when r = 2 then val end as val2,
case when r = 3 then id end as id3, case when r = 3 then val end as val3
from (
select key ||'_'|| listagg(id ||':' ||val, '_')
within group (order by id) over (partition by key) as unique_id,
key, id, val,
row_number() over (partition by key order by id) as r
from foo
)
)
group by unique_id, key
order by key;
UNIQUE_ID KEY ID1 VAL1 ID2 VAL2 ID3 VAL3
----------------- ---- ---- ---- ---- ---- ---- ----
47_1:97_2:98_3:99 47 1 97 2 98 3 99
48_4:100_5:101 48 4 100 5 101
49_6:102 49 6 102
Can't help feeling there ought to be a simpler way though...