Oracle SQL regexp_substr

Question

I have a query which fetches value matching the pattern, I want it to fetch all prefvalue instead of only CEROTG

SELECT regexp_substr('prefvalue:CEROTG-2 prefvalue:CEROTG prefvalue:CEROTG_1', 'prefvalue:([[:alnum:]_]+)') as Result from dual

Current Output

prefvalue:CEROTG

Expected Output

prefvalue:CEROTG
prefvalue:CEROTG-2
prefvalue:CEROTG_1

Answer 1

One option uses a recursive query:

with 
    data as (select 'prefvalue:CEROTG-2 prefvalue:CEROTG prefvalue:CEROTG_1' str from dual),
    cte(str, res, lvl) as (
        select str, regexp_substr(str, 'prefvalue:([[:alnum:]_-]+)'), 1 lvl from data
        union all
        select str, regexp_substr(str, 'prefvalue:([[:alnum:]_-]+)', 1, lvl + 1), lvl + 1 
        from cte 
        where lvl < regexp_count(str, 'prefvalue:([[:alnum:]_-]+)')
    )
select res from cte

Demo on DB Fiddle :

| RES                |
| :----------------- |
| prefvalue:CEROTG-2 |
| prefvalue:CEROTG   |
| prefvalue:CEROTG_1 |

Answer 2

You can use simple string functions in a recursive subquery-factoring clause:

WITH rsqfc ( entry_data, start_pos, end_pos ) AS (
  SELECT entry_data, 1, INSTR( entry_data, ' ', 1 )
  FROM   prefdir_entrydata
UNION ALL
  SELECT entry_data, end_pos + 1, INSTR( entry_data, ' ', end_pos + 1 )
  FROM   rsqfc
  WHERE  end_pos > 0
)
SELECT CASE end_pos
       WHEN 0
       THEN SUBSTR( entry_data, start_pos )
       ELSE SUBSTR( entry_data, start_pos, end_pos - start_pos )
       END AS value
FROM   rsqfc

Which, for your sample data:

CREATE TABLE prefdir_entrydata ( entry_data ) AS
SELECT 'prefvalue:CEROTG-2 prefvalue:CEROTG prefvalue:CEROTG_1' FROM DUAL;

Outputs:

\n|  VALUE |\n|  :----------------- | \n|  prefvalue:CEROTG-2 |\n|  prefvalue:CEROTG |\n|  prefvalue:CEROTG_1 |\n

db<>fiddle here

---

An example that handles multiple input rows is:

WITH rsqfc ( id, entry_data, start_pos, end_pos ) AS (
  SELECT id, entry_data, 1, INSTR( entry_data, ' ', 1 )
  FROM   prefdir_entrydata
  WHERE  dist_name_short = 'prefentry=imagerepository,prefgroup=cdi_globals,prefgroup=component,prefgroup=system,prefcontext=default,prefroot=prefroot'
UNION ALL
  SELECT id, entry_data, end_pos + 1, INSTR( entry_data, ' ', end_pos + 1 )
  FROM   rsqfc
  WHERE  end_pos > 0
)
SELECT id,
       CASE end_pos
       WHEN 0
       THEN SUBSTR( entry_data, start_pos )
       ELSE SUBSTR( entry_data, start_pos, end_pos - start_pos )
       END AS value
FROM   rsqfc
ORDER BY id, start_pos

Which, for the test data:

CREATE TABLE prefdir_entrydata ( id, entry_data, dist_name_short ) AS
SELECT 1,
       'prefvalue:CEROTG-2 prefvalue:CEROTG prefvalue:CEROTG_1',
       'prefentry=imagerepository,prefgroup=cdi_globals,prefgroup=component,prefgroup=system,prefcontext=default,prefroot=prefroot'
FROM   DUAL UNION ALL
SELECT 2,
       'prefvalue:CEROTG-2a prefvalue:CEROTG_1v2',
       'prefentry=imagerepository,prefgroup=cdi_globals,prefgroup=component,prefgroup=system,prefcontext=default,prefroot=prefroot'
FROM   DUAL;

Outputs:

\nID | VALUE               \n-: |  :------------------- \n 1 |  prefvalue:CEROTG-2  \n 1 |  prefvalue:CEROTG    \n 1 |  prefvalue:CEROTG_1  \n 2 |  prefvalue:CEROTG-2a \n 2 |  prefvalue:CEROTG_1v2\n

db<>fiddle here

Answer 3

WITH tbl(DATA) AS (
  SELECT 'prefvalue:CEROTG-2 prefvalue:CEROTG prefvalue:CEROTG_1'
  FROM dual
)
SELECT REGEXP_SUBSTR(DATA, '(.*?)( |$)', 1, LEVEL, NULL, 1) ELEMENT
FROM tbl
CONNECT BY LEVEL <= REGEXP_COUNT(DATA, ' ')+1; 

ELEMENT                                               
------------------------------------------------------
prefvalue:CEROTG-2                                    
prefvalue:CEROTG                                      
prefvalue:CEROTG_1                                    

3 rows selected.