This document discusses various options for pivoting and aggregating data in Oracle SQL, including sys_connect_by_path, MAX(DECODE), and LISTAGG. It provides syntax examples and explanations for LISTAGG, which allows concatenating column values within groups. It also presents a user-defined function to modify LISTAGG output to remove duplicate values separated by a delimiter.

1. Yes, I demonstrated this in 2013 at Coder’s Corner, but I’ve
learned more
Bryan L. Mack
04/15/2016

2. Pivoting Data

3. Pivot Options –
sys_connect_by_path
Cumbersome, but it works with no sequence number.
Still – too lengthy for my taste.

4. Pivot Options – max(decode(
When you have a sequence number
 If no sequence exists, you can create one in-line
 You need to know how many entries exist
 May need to rtrim the final delimiter or do a REPLACE on extra delimiters

5. ListAgg
Source: http://docs.oracle.com

6. Why use ListAgg?
 Dynamic (knows how many rows exist in a group, so is
superior to using MAX(DECODE(<seq#
 Can use any delimiter you’d like
 Can concatenate multiple fields
 Simplistic code

7. ListAgg Syntax – Required
Components
Required Components
 Column(s) to be aggregated
 The WITHIN GROUP keywords
 The ORDER BY clause within the grouping
GROUP BY must be used for the entire block

8. Example #1

9. Example #2 – Repeated Values

10. Example #2 – 2 ways to get rid of
duplicates
Option #1 – create distinct data set and pull from it:

11. Example #2 – 2 ways to get rid of
duplicates
 Option #2 – Use Regular Expressions

12. Side note:
If using the RegExp method and your delimiter is not
“comma space” (‘, ‘) – then replace the three “, “
references on the 4th line of code with your delimiter.
Here is an example with a colon and no space:

13. Function to do this for you
create or replace function distinct_listagg
(listagg_in varchar2,
delimiter_in varchar2)
return varchar2
as
hold_result varchar2(4000);
begin
select rtrim( regexp_replace( (listagg_in)
, '([^'||delimiter_in||']*)('||
delimiter_in||'1)+($|'||delimiter_in||')', '13'), ',')
into hold_result
from dual;
return hold_result;
end;

14. Function to do this for you
 Example: The listagg function as such:
 listagg(ia.mif_value,',') within GROUP (ORDER
BY ia.person_uid, ia.academic_period)
 Returns: CCA,CCA,CCA,CCD,CCD,CCD,CCD

 Example using my function:
 distinct_listagg(listagg(ia.mif_value,',') within GROUP
(ORDER BY ia.person_uid, ia.academic_period),
 ',')
 Returns: CCA,CCD

15. Questions?
fleetmack@gmail.com