REGEXP_SUBSTR - using nth occurence, how can I include null?

Question

Hi
Running the following:
select REGEXP_SUBSTR('1|2|3|4|5||7|8|9|10','[^|]+', 1, 5) from dual
UNION ALL
select REGEXP_SUBSTR('1|2|3|4|5||7|8|9|10','[^|]+', 1, 6) from dual
UNION ALL
select REGEXP_SUBSTR('1|2|3|4|5||7|8|9|10','[^|]+', 1, 7) from dual
UNION ALL
select REGEXP_SUBSTR('1|2|3|4|5||7|8|9|10','[^|]+', 1, 8) from dualGives:
5
7
8
9
How can I get it to produce:
5
7
8
Please?
In other words, I want to not skip the null.
Thanks

Answer 1

Perhaps using a replace of || to | | in the statement will do the trick :)
I want to avoid writing a procedure.You have problems on inputs with | as first character too, replacing || with | | won't solve that problem. That's why I suggest you to don't try that way.
The solution I posted before, the one using regexp_replace instead of regexp_substr, was good for it.
Processing ...
with input as (
          select '|2|3|4|5||7|8|9|10' as chars
          from dual
     ),positions as (
          select 5 as pos
          from dual
          union all
          select 6 as pos
          from dual
          union all
          select 7 as pos
          from dual
          union all
          select 8 as pos
          from dual
select regexp_replace(chars,'^([^|]*\|?){'||to_char(pos-1)||'}([^|]*).*$','\2'),
     nullif(regexp_substr(replace(chars,'||','| |'),'[^|]+',1,pos),' ')
from input
     cross join positions
Query finished, retrieving results...
    REGEXP_REPLACE(CHARS,'^([^|]*\|?){'||TO_CHAR(POS-1)||'}([^|]*).*$','\2')           NULLIF(REGEXP_SUBSTR(REPLACE(CHARS,'||','||'),'[^|]+',1,POS),'')      
5                                                                                                                                                            
                                                                                 7                                                                           
7                                                                                8                                                                           
8                                                                                9                                                                           
4 row(s) retrievedBye Alessandro