SQL正则表达式根据分隔符'/n'将列（字符串）拆分为多行

Question

I have to split a column to multiple rows. The column stores string, and we have to split delimiter based on '/n'

Have written the below query. But not able to specify ^[/n] . The other 'n' in the string is also getting removed. Please help to parse the string

WITH sample AS 
( SELECT 101 AS id, 
        'Name' test, 
        '3243243242342342/n12131212312/n123131232/n' as attribute_1, 
        'test value/nneenu not/nhoney' as attribute_2
   FROM DUAL 
) 
-- end of sample data
SELECT id,
       test,
       regexp_substr(attribute_1,'[^/n]+', 1, column_value),
       regexp_substr(attribute_2,'[^/]+', 1, column_value)
  FROM sample,
       TABLE(
         CAST(
           MULTISET(SELECT LEVEL 
                       FROM dual  
                    CONNECT BY LEVEL <= LENGTH(attribute_1) - LENGTH(replace(attribute_1, '/n')) + 1
                   ) AS sys.OdciNumberList
         )
       )
 WHERE regexp_substr(attribute_1,'[^/n]+', 1, column_value) IS NOT NULL
/

Answer 1

you need to use class [[:cntrl:]] and '[^/n]+' is not syntactically good either.

the escape char is '\' and you cannot use [] to "wrap" special chars, you need to use () instead.(that is grouping)

if you want to ignore CR (eg'\n') , use [^[:cntrl:]] in the sec param in the regexp_substr

more help: http://psoug.org/snippet/Regular-Expressions--Regexp-Cheat-Sheet_856.htm

Answer 2

Assumption

/n is supposed to mean \n to match a newline ( strictly [Posix] speaking a LF character (hex x0a) ).

If this assumption is wrong, use (^|/n)(([^/]|/+[^n])+) as your regex and extract the part of interest using regexp_substr(attribute_1,'(^|/n)(([^/]|/+[^n])+)', 1, column_value, '', 2) .

Solution

You cannot specify control characters in escape syntax within character classes. Using the posix character class [:cntrl:] works but suffers from the other characters included; for practical purposes, TAB ( #x09 ) might be a nuisance.

However, you can specify all characters in a regex character class composing the pattern string from literals and calls to the chr function:

   -- ...
    '3243243242342342'||chr(13)||chr(10)||'12131212312'||chr(13)||chr(10)||'123131232'||chr(13)||chr(10) as attribute_1, 
    'test value'||chr(13)||chr(10)||'neenu not'||chr(13)||chr(10)||'honey' as attribute_2
   -- ...
   regexp_substr(attribute_1,'[^'||chr(13)||chr(10)||']+', 1, column_value),
   regexp_substr(attribute_2,'[^'||chr(13)||chr(10)||']+', 1, column_value)
   -- ...

You may want to check out the following test queries in sqlplus (the cr/lfs are part of the literals; copy into a text editor, check that the cr/lfs are preserved, re-insert if not, drop the result in sqlplus):

select regexp_substr('adda
yxcv','[^'||CHR(10)||CHR(13)||']+', 1, 2) from dual;
select regexp_substr('ad'||CHR(9)||'da
yxcv','[^[:cntrl:]]+', 1, 2) from dual;

Answer 3

with test as (select 'ABC' || chr(13) || 'DEF' || chr(13) || 'GHI' || chr(13) || 'JKL' || chr(13) || 'MNO' str from dual)
select regexp_substr (str, '[^' || chr(13) || ']+', 1, rownum) split
from test
connect by level <= length (regexp_replace (str, '[^' || chr(13) || ']+'))  + 1

Answer 4

First choice would be to fix the data model as data stored this way is not optimal. At any rate, try this version with some more test data. I tweaked the regex's:

WITH sample AS 
( SELECT 101 AS id, 
        'Name' test, 
        '3243243242342342/n12131212312/n123131232/n' as attribute_1, 
        'test value/nneenu not/nhoney' as attribute_2
   FROM DUAL 
) 
-- end of sample data
SELECT id,
       test,
       regexp_substr(attribute_1,'(.*?)(/n|$)', 1, column_value, NULL, 1),
       regexp_substr(attribute_2,'(.*?)(/n|$)', 1, column_value, NULL, 1)
  FROM sample,
       TABLE(
         CAST(
           MULTISET(SELECT LEVEL 
                       FROM dual  
                    --CONNECT BY LEVEL <= LENGTH(attribute_1) - LENGTH(replace(attribute_1, '/n')) + 1
                      -- Counts substrings ending with the delimiter.
                      CONNECT BY LEVEL <= REGEXP_COUNT(attribute_1, '.*?/n')                    
                   ) AS sys.OdciNumberList
         )
       )
 WHERE regexp_substr(attribute_1,'(.*?)(/n|$)', 1, column_value, NULL, 1) IS NOT NULL
/