Splitting comma separated values in Oracle - sql

Question

I have column in my database where the values are coming like the following:
3862,3654,3828
In dummy column any no. of comma separated values can come. I tried with following query but it is creating duplicate results.
select regexp_substr(dummy,'[^,]+',1,Level) as dummycol
from (select * from dummy_table)
connect by level <= length(REGEXP_REPLACE(dummy,'[^,]+'))+1
I am not understanding the problem. Can anyone can help?

Answer 1

Works perfectly for me -
SQL> WITH dummy_table AS(
2 SELECT '3862,3654,3828' dummy FROM dual
3 )
4 SELECT trim(regexp_substr(dummy,'[^,]+',1,Level)) AS dummycol
5 FROM dummy_table
6 CONNECT BY level <= LENGTH(REGEXP_REPLACE(dummy,'[^,]+'))+1
7 /
DUMMYCOL
--------------
3862
3654
3828
SQL>
There are many other ways of achieving it. Read Split single comma delimited string into rows.
Update Regarding the duplicates when the column is used instead of a single string value. Saw the use of DBMS_RANDOM in the PRIOR clause to get rid of the cyclic loop here
Try the following,
SQL> WITH dummy_table AS
2 ( SELECT 1 rn, '3862,3654,3828' dummy FROM dual
3 UNION ALL
4 SELECT 2, '1234,5678' dummy FROM dual
5 )
6 SELECT trim(regexp_substr(dummy,'[^,]+',1,Level)) AS dummycol
7 FROM dummy_table
8 CONNECT BY LEVEL <= LENGTH(REGEXP_REPLACE(dummy,'[^,]+'))+1
9 AND prior rn = rn
10 AND PRIOR DBMS_RANDOM.VALUE IS NOT NULL
11 /
DUMMYCOL
--------------
3862
3654
3828
1234
5678
SQL>
Update 2
Another way,
SQL> WITH dummy_table AS
2 ( SELECT 1 rn, '3862,3654,3828' dummy FROM dual
3 UNION ALL
4 SELECT 2, '1234,5678,xyz' dummy FROM dual
5 )
6 SELECT trim(regexp_substr(t.dummy, '[^,]+', 1, levels.column_value)) AS dummycol
7 FROM dummy_table t,
8 TABLE(CAST(MULTISET
9 (SELECT LEVEL
10 FROM dual
11 CONNECT BY LEVEL <= LENGTH (regexp_replace(t.dummy, '[^,]+')) + 1
12 ) AS sys.OdciNumberList)) LEVELS
13 /
DUMMYCOL
--------------
3862
3654
3828
1234
5678
xyz
6 rows selected.
SQL>

Answer 2

Giving a PL/SQL example where parsing over a table with an ID and column name. This will parse and print out each ID and the parsed value which could then be inserted into a new table or used in some other way.
Input
Column_ID Column_Name
123 (3862,3654,3828)
Output
Column_ID Column_Name
123 3862
123 3654
123 3828
PL/SQL Code
declare
table_name1 varchar2(1000);
string_to_parse varchar2(2000); -- assign string to table name
string_length number := 0; -- string length for loop
string_value varchar2(2000); -- string value to store value in
column_id number;
begin
--some table in the format '123' as column_id, '(3862,3654,3828)' as column_name
--remove the parenthesis or other special characters if needed
update some_table t
set t.column_name = regexp_replace(t.column_name,'\(|\)','');
commit;
for i in (
select * from some_table
) loop
column_id := i.column_id; --assign the id of the colors
string_to_parse := i.column_name; -- assign string to be parsed
if string_to_parse is null then
--at this point insert into a new table, or do whatever else you need
dbms_output.put_line(column_id || ' ' || string_value);
else
--String to parse is the comma
string_to_parse := string_to_parse||',';
string_length := length(string_to_parse) - length(replace(string_to_parse,',',''));
-- Loop through string from parameter
for i in 1 .. string_length loop
-- [^,] matches any character except for the ,
select regexp_substr(string_to_parse,'[^,]+',1,i)
into string_value -- stores value into string_value
from dual; -- dual is a dummy table to work around
--at this point insert into a new table, or do whatever else you need
dbms_output.put_line(column_id || ' ' || string_value);
--clear out the string value
string_value := null;
end loop;
end if;
end loop;
end;