Easy Question: How to split concatenated string into multiple rows?

Question

Hi folks,
this might be an easy question.
How can I split a concatenated string into multiple rows using SQL query?
INPUT:
select 'AAA,BBB,CC,DDDD' as data from dualDelimiter = ','
Expected output:
data
AAA
BBB
CCC
DDDDI'm looking for something kind of "an opposite for 'sys_connect_by_path'" function.
Thanks,
Tomas

Answer 1

Here is the SUBSTR/INSTR version of the solution:
SQL> WITH test_data AS
  2  (
  3          SELECT ',' || 'AAA,BBB,CC,DDDD' || ',' AS DATA FROM DUAL
  4  )
  5  SELECT  SUBSTR
  6          (
  7                  DATA
  8          ,       INSTR
  9                  (
10                          DATA
11                  ,       ','
12                  ,       1
13                  ,       LEVEL
14                  ) + 1
15          ,       INSTR
16                  (
17                          DATA
18                  ,       ','
19                  ,       1
20                  ,       LEVEL + 1
21                  ) -
22                  INSTR
23                  (
24                          DATA
25                  ,       ','
26                  ,       1
27                  ,       LEVEL
28                  ) - 1
29          )       AS NEW_STRING
30  FROM    test_data
31  CONNECT BY LEVEL <= LENGTH(REGEXP_REPLACE(DATA,'[^,]','')) - 1
32  /
NEW_STRING
AAA
BBB
CC
DDDD