Create Function SQL - sql

Question

I need to create a function that would split string by element.
'a1,a2,a1,a3' and result should be:
Value
Counter
a1
2
a2
1
a3
1
This is example of my code (but it needs to work)
CREATE OR REPLACE FUNCTION SPLIT_STRING (
IN_STRING VARCHAR(1000),
IN_DELIM VARCHAR(20))
RETURNS TABLE (CNT INT)
LANGUAGE SQL
READS SQL DATA
BEGIN
DECLARE I INT DEFAULT 0;
DECLARE CNT INT DEFAULT 0;
WHILE I < LENGTH(IN_STRING)
DO
IF SUBSTR(IN_STRING, I, 1) = IN_DELIM THEN SET CNT = CNT + 1;
END IF;
SET I = I + 1;
END WHILE;
RETURN CNT;
END;
select SPLIT_STRING('a1,a2,a1,a3', ',') from SYSIBM.SYSDUMMY1

Answer 1

There is no need to create such a function in Db2 for LUW.
You may use a built-in functionality.
select x.tok as value, count (1) as counter
from
-- Here is your table reference
(values 'a1,a2,a1,a3') mytab (str)
, xmltable
(
'for $id in tokenize($s, ",") return <i>{string($id)}</i>'
passing
mytab.str as "s"
columns
tok varchar(4000) path '.'
) x
group by x.tok
VALUE
COUNTER
a1
2
a2
1
a3
1
Update
The same with a table function:
CREATE OR REPLACE FUNCTION SPLIT_STRING
(
IN_STRING VARCHAR(1000)
, IN_DELIM VARCHAR(20)
)
RETURNS TABLE (TOKEN VARCHAR (100), CNT INT)
LANGUAGE SQL
READS SQL DATA
RETURN
select x.tok as value, count (1) as counter
from xmltable
(
'for $id in tokenize($s, $p) return <i>{string($id)}</i>'
passing
IN_STRING as "s"
, IN_DELIM as "p"
columns
tok varchar (1000) path '.'
) x
group by x.tok
select *
from table (SPLIT_STRING ('a1,a2,a1,a3', ','))
TOKEN
CNT
a1
2
a2
1
a3
1
fiddle