Separate comma separate values in Oracle

Question

I have a database column which contains comma separated values. Is there any way to get the individual values from this column into different rows without using regular expression in Oracle.

Answer 1

Create a small function that converts the delimited list to a collection and then use a TABLE() collection expression to include it as separate rows:

PL/SQL Function:

CREATE OR REPLACE FUNCTION split_String(
  i_str    IN  VARCHAR2,
  i_delim  IN  VARCHAR2 DEFAULT ','
) RETURN SYS.ODCIVARCHAR2LIST DETERMINISTIC
AS
  p_result       SYS.ODCIVARCHAR2LIST := SYS.ODCIVARCHAR2LIST();
  p_start        NUMBER(5) := 1;
  p_end          NUMBER(5);
  c_len CONSTANT NUMBER(5) := LENGTH( i_str );
  c_ld  CONSTANT NUMBER(5) := LENGTH( i_delim );
BEGIN
  IF c_len > 0 THEN
    p_end := INSTR( i_str, i_delim, p_start );
    WHILE p_end > 0 LOOP
      p_result.EXTEND;
      p_result( p_result.COUNT ) := SUBSTR( i_str, p_start, p_end - p_start );
      p_start := p_end + c_ld;
      p_end := INSTR( i_str, i_delim, p_start );
    END LOOP;
    IF p_start <= c_len + 1 THEN
      p_result.EXTEND;
      p_result( p_result.COUNT ) := SUBSTR( i_str, p_start, c_len - p_start + 1 );
    END IF;
  END IF;
  RETURN p_result;
END;
/

Sample Data:

CREATE TABLE table_name ( id, list ) AS
SELECT 1, 'a,b,c,d' FROM DUAL UNION ALL -- Multiple items in the list
SELECT 2, 'e'       FROM DUAL UNION ALL -- Single item in the list
SELECT 3, NULL      FROM DUAL UNION ALL -- NULL list
SELECT 4, 'f,,g'    FROM DUAL;          -- NULL item in the list

Query:

SELECT t.id,
       v.column_value AS value,
       ROW_NUMBER() OVER ( PARTITION BY id ORDER BY ROWNUM ) AS lvl
FROM   table_name t
       LEFT OUTER JOIN
       TABLE( split_String( t.list ) ) v
       ON ( 1 = 1 )

Output:

        ID VALUE          LVL
---------- ------- ----------
         1 a                1 
         1 b                2 
         1 c                3 
         1 d                4 
         2 e                1 
         3 (NULL)           1 
         4 f                1 
         4 (NULL)           2 
         4 g                3 

Answer 2

Here's an SO post that uses XML instead of regexp_substr.

Hope that helps

EDIT: For those who don't want to follow the link, a simple example would be:

with testdata as (
  select 'a,test,string,for,splitting,values' as col from dual
)
select extractvalue(x.column_value, 'e') as tokens
from testdata, xmltable ('e' passing xmlparse( content  '<e>' || replace(col, ',', '</e><e>') || '</e>')) x;

Output:

TOKENS
a
test
string
for
splitting
values

There are limitations just like with regexp solution. But this approach does not use regexp as requested.