concate or segregate strings based on requirement - sql

Question

USER_ID COLUMN1 COLUMN2
JOHN 24 CA
JOHN 24 LA
JOHN 63 CA
JOHN 63 LA
JOHN 66 CA
JOHN 66 LA
JOHN 9 AF
JOHN 9 AL
JOHN 9 AW
JOHN 9 DF
Required output:
USER_ID RESULT
JOHN 24~CA-LA + 63~CA-LA + 66~CA-LA + 9~AF-AL-AW-DF
This is my requirement. I am trying listagg():
select USER_ID,
(listagg(case when seqnum_p = 1 then COLUMN1 end, '-') within group (order by COLUMN1) ||
'~' ||
listagg(case when seqnum_b = 1 then COLUMN2 end, '-') within group (order by COLUMN2)
) as result
from (select TABLE.*,
row_number() over (partition by USER_ID, COLUMN1 order by COLUMN1) as seqnum_p,
row_number() over (partition by USER_ID, COLUMN2 order by COLUMN2) as seqnum_b
from TABLE
)
group by USER_ID;
Current output:
JOHN || AF-AL-AW-CA-DF-LA~24-63-66-9

Answer 1

You can do two levels of aggregation instead of dealing with the row numbers:
select user_id,
listagg(tmp, ' + ') within group (order by tmp) as result
from (
select user_id,
column1 ||'~'|| listagg(column2, '-') within group (order by column2) as tmp
from your_table
group by user_id, column1
)
group by user_id
order by user_id;
USER RESULT
---- --------------------------------------------------
JOHN 24~CA-LA + 63~CA-LA + 66~CA-LA + 9~AF-AL-AW-DF
The inner query gives you the first level:
USER TMP
---- --------------------------------------------------
JOHN 9~AF-AL-AW-DF
JOHN 24~CA-LA
JOHN 63~CA-LA
JOHN 66~CA-LA
and the outer level further aggregates those into a single string per user.
The order-by in the outer query aggregation is of a string starting with a number, which puts '9~...' after '24~...', which would normally be odd but seems to be what you expect.
If you actually wanted them in numerical column-1-order you can include that in the subquery and use it for ordering:
select user_id,
listagg(tmp, ' + ') within group (order by column1) as result
from (
select user_id, column1,
column1 ||'~'|| listagg(column2, '-') within group (order by column2) as tmp
from your_table
group by user_id, column1
)
group by user_id
order by user_id;
USER RESULT
---- --------------------------------------------------
JOHN 9~AF-AL-AW-DF + 24~CA-LA + 63~CA-LA + 66~CA-LA