Regexp Like

Question

Hi
I have created this sample data
with test_data as
SELECT null as data_str
FROM dual
UNION ALL
SELECT 'A' from dual
UNION ALL
select 'A|B' from dual
UNION ALL
select '|A|B' from dual
select * from test_dataBy using regexp_like operator I would like to display the below output
null
A
A|BI tried this
with test_data as
SELECT null as data_str
FROM dual
UNION ALL
SELECT 'A' from dual
UNION ALL
select 'A|B' from dual
--UNION ALL
--select '|A|B' from dual
select * from test_data
--where regexp_like like '%|%'
where regexp_like (data_str,'^[null|||'|'||]*$')   But threw this error
ORA-00996: the concatenate operator is ||, not |
00996. 00000 -  "the concatenate operator is ||, not |"
*Cause:   
*Action:
Error at Line: 188 Column: 17Am not able to proceed further. Please help!
Regards,
Achyut Kotekal

Answer 1

Hi, Achyut,
Achyut K wrote:
By using regexp_like operator I would like to display the below output
null
A
A|B
Why just those 2 rows? Explain the rules, so we can find a solution that applies those rules to all data, not just a small sample set. You may want to post a few more rows of sample data, to make it more clear what kinds of strings you want to include or exclude from the results.
If you want to find strings that contain either just a single non-pipe charachter (such as 'A') or 2 or more such characters, each separated by a pipe (such as 'A|B' or 'A|X|A|Y|A|Z') then you can do this:
SELECT     *
FROM     test_data
WHERE     REGEXP_LIKE ( data_str
              , '^'          || -- Beginning of string
                '[^|]'          || -- Exactly 1 non-pipe
                '('          || -- a group consisiting of ...
                   '\|'          || --     a pipe, followed by
                '[^|]'          || --       any 1 character except a pipe
                ')*'          || -- group occurs 0 or more  times
                '$'             -- end of string
; I tried this
with test_data as
SELECT null as data_str
FROM dual
UNION ALL
SELECT 'A' from dual
UNION ALL
select 'A|B' from dual
--UNION ALL
--select '|A|B' from dual
select * from test_data
--where regexp_like like '%|%'
where regexp_like (data_str,'^[null|||'|'||]*$')   But threw this error
ORA-00996: the concatenate operator is ||, not |
00996. 00000 -  "the concatenate operator is ||, not |"
*Cause:   
*Action:
Error at Line: 188 Column: 17
Always format your code, to make it easier to spot the extent of quotes and bracketed expressions.
For example, this mkae the problem much clearer
SELECT  *
FROM      test_data
--where     regexp_like like '%|%'
WHERE   REGEXP_LIKE ( data_str
               , '^[null|||'     -- This is a well-formed string literal
                |           -- What is this supposed to be?
                '||]*$'          -- This is another well-formed string literal
;Since I don't know what you want, I can't way exactly what you should do instead.