Character string buffer too small - sql

Question

I have select:
select v.accs, v.currency,v.amount,v.drcr_ind, count(*) qua,wm_concat(ids) npx_IDS,
wm_concat(px_dtct) npx_DTCT
from table v
group by accs, currency, amount, drcr_ind
but i get error ORA-06502: PL/SQL: : character string buffer too small if i'll remove one string, because sometimes (when v.accs= 3570) count(*) = 215
but when i try to skip using wm_concat for v.accs= 3570 for example this way:
select v.accs, v.currency,v.amount,v.drcr_ind, count(*) qua,wm_concat(ids) npx_IDS,
(case when v.accs = 3570 then wm_concat(px_dtct) else 'too many' end) npx_DTCT
from table v
group by accs, currency, amount, drcr_ind
i still have the same error message. But why?

Answer 1

You concatenate results from a query. This query can result in a lot of rows so eventually you will run out of string length. Maybe concatenation is not the way to go here. Depends on what you want to achieve of course.

Answer 2

Why? Because you still use wm_concat for accs=3570... swap the THEN and ELSE part of your CASE expression
select v.accs, v.currency,v.amount,v.drcr_ind, count(*) qua,wm_concat(ids) npx_IDS,
(case when v.accs = 3570 then 'too many' else wm_concat(px_dtct) end) npx_DTCT
from table v group by accs, currency, amount, drcr_ind

Answer 3

First, as it has already been told, you have to switch then and else clauses in your query.
Then, I guess you should also similarily process your second wm_concat, the one that works with ids.
select v.accs, v.currency,v.amount,v.drcr_ind, count(*) qua,
(case when v.accs = 3570 then 'too many' else wm_concat(ids) end) npx_IDS,
(case when v.accs = 3570 then 'too many' else wm_concat(px_dtct) end) npx_DTCT
from table v
group by accs, currency, amount, drcr_ind
And, finally, why do you think that only v.accs = 3570 is able to bring 06502 error in front of you? I suppose you should handle all of them.