split the regular expression and loop through - plsql

Question

I need to loop through inside a join thats what I think I have written.
I am posting the code.
select listagg(request_num,',') within group (order by request_num) as request_num,segmentation_name from (
select MST.REQUEST_NUM,seg_dtls.SEGMENT_NAME,LAST_UPDATED_date,seg_dtls.segmentation_name from
(select * from rp_sr_master ) Mst,
(select SUBSTR(ANSWER,1,INSTR (ANSWER, '~', 1)-1) AS SM_ID,sr_id from rp_sR_details
WHERE Q_ID in (SELECT Q_ID FROM RP_QUESTIONS WHERE field_id='LM_LRE_Q6')
) Dtls, (select SM_ID, SQL_STATEMENT, CREATION_DATE, UPDATED_DATE, SEGMENT_NAME,segmentation_name ,TOTAL_COUNT
from rp_sEGMENT_master ) seg_dtls
where Dtls.SM_ID=seg_dtls.SM_ID
and Dtls.sr_id=Mst.sr_id)
group by segmentation_name;
The problem I am facing here is in the following,
(select SUBSTR(ANSWER,1,INSTR (ANSWER, '~', 1)-1) AS SM_ID,sr_id from rp_sR_details
WHERE Q_ID in (SELECT Q_ID FROM RP_QUESTIONS WHERE field_id='LM_LRE_Q6')
)
In the above code, answer will be something like this:
2603~NG non IaaS IT Professional^2600~NG non IaaS Senior IT^2598~NG data profiling SENIOR IT professional^2595~Nigeria data profiling IT professiona
It only picks the first number that is 2603 and others will be left out.
Is there any way I can loop through all the number in that 'ANSWER'.
I am looking for ideas.
Thanks.

Answer 1

One idea is to use a method for splitting a comma delimited string into rows, you can find examples of this method in the following answers:
Splitting comma separated values in Oracle
How can I use regex to split a string, using a string as a delimiter?
The above solutions use regexp_substr function.
If you dig into details of Oracle's REGEXP_SUBSTR function you wil find that there is optional position parameter there.
This parameter can be combined with a sulution shown in this answer:
SQL to generate a list of numbers from 1 to 100
(that is SELECT LEVEL n FROM DUAL CONNECT BY LEVEL <= 100) in the below way:
with xx as (
select '2603~NG non IaaS IT Professional^2600~NG non IaaS Senior '
|| 'IT^2598~NG data profiling SENIOR IT professional^2595~Nigeria '
|| 'data profiling IT professiona' as answer
from dual
)
select LEVEL AS n, regexp_substr( answer, '\d+', 1, level) as nbr
from xx
connect by level <= 6
;
The above query produces the following result:
N |NBR |
--|-----|
1 |2603 |
2 |2600 |
3 |2598 |
4 |2595 |
5 | |
6 | |
What we need is to eliminate null values from the resultset, it can be done using a simple condition IS NOT NULL
with xx as (
select '2603~NG non IaaS IT Professional^2600~NG non IaaS Senior '
|| 'IT^2598~NG data profiling SENIOR IT professional^2595~Nigeria '
|| 'data profiling IT professiona' as answer
from dual
)
select LEVEL AS n, regexp_substr( answer, '\d+', 1, level) as nbr
from xx
connect by regexp_substr( answer, '\d+', 1, level) IS NOT NULL
;
N |NBR |
--|-----|
1 |2603 |
2 |2600 |
3 |2598 |
4 |2595 |
The above query works perfect for a single record, but gets confused when we try to parse 2 or more rows. Luckily there is another answer on SO that helps to solve this issue:
Is there any alternative for OUTER APPLY in Oracle?
-- source data
WITH xx as (
select 1 AS id,
'2603~NG non IaaS IT Professional^2600~NG non IaaS Senior '
|| 'IT^2598~NG data profiling SENIOR IT professional^2595~Nigeria '
|| 'data profiling IT professiona' as answer
from dual
UNION ALL
select 2 AS id,
'11111~NG non IaaS IT Professional^22222~NG non IaaS Senior '
|| 'IT^2598~NG data 33333 profiling SENIOR IT professional^44~Nigeria '
|| 'data profiling 5 IT professiona 66' as answer
from dual
)
-- end of source data
SELECT t.ID, t1.n, t1.nbr
FROM xx t
CROSS JOIN LATERAL (
select LEVEL AS n, regexp_substr( t.answer, '\d+', 1, level) as nbr
from dual
connect by regexp_substr( t.answer, '\d+', 1, level) IS NOT NULL
) t1;
the above query parses numbers from two records and displays then in the following form:
ID |N |NBR |
---|--|------|
1 |1 |2603 |
1 |2 |2600 |
1 |3 |2598 |
1 |4 |2595 |
2 |1 |11111 |
2 |2 |22222 |
2 |3 |2598 |
2 |4 |33333 |
2 |5 |44 |
2 |6 |5 |
2 |7 |66 |
I belive you will manage to merge this simple "parsing" query into your main query.