Как создать функцию SPLIT_STRING в Db2

Question

Я пытаюсь написать функцию db2, ниже приведен код

CREATE OR REPLACE FUNCTION SPLIT_STRING (INPUT VARCHAR(8000), DELIMITER 
CHAR(1) DEFAULT ',')
RETURNS TABLE (str VARCHAR(8000))
SPECIFIC SPLIT_STRING
LANGUAGE SQL
DETERMINISTIC
NO EXTERNAL ACTION
BEGIN ATOMIC
 DECLARE @MSG VARCHAR(30)
 SET @MSG ='INVALID INPUT'
 IF (INPUT IS NULL) THEN RETURN @MSG
ELSE
 RETURN
 WITH R1 (str, REMAINDER) AS
 (SELECT SUBSTR(INPUT, 1, LOCATE(DELIMITER, INPUT) -1) AS str,
    SUBSTR(INPUT, LOCATE(DELIMITER, INPUT) +1 , LENGTH(INPUT)) 
 REMAINDER FROM SYSIBM.SYSDUMMY1

UNION ALL
SELECT SUBSTR(REMAINDER, 1, LOCATE(DELIMITER, REMAINDER)-1) AS str,
   SUBSTR(REMAINDER, LOCATE(DELIMITER, REMAINDER)+1, LENGTH(REMAINDER)) 
REMAINDER  FROM R1
WHERE LOCATE(DELIMITER, REMAINDER) > 0

UNION ALL
SELECT SUBSTR(REMAINDER, LOCATE(DELIMITER, REMAINDER)+1, 
LENGTH(REMAINDER)) AS str,'' AS REMAINDER  FROM R1 WHERE REMAINDER <> ''
AND LOCATE(DELIMITER, REMAINDER) = 0

)SELECT str FROM R1
END IF
END;

Если я удаляю условие IF, которое используется для проверки входных параметров, функция создается нормально, иначе получается ошибка ниже.

DB21034E  The command was processed as an SQL statement because it was 
not a valid Command Line Processor command.  During SQL processing it returned:SQL0104N  An unexpected token "SET" was found following "RE @MSG VARCHAR(30) ".  Expected tokens may include:  <SQL_variable_declarations>".  LINE NUMBER=8.  SQLSTATE=42601

Answer 1

Разветвитель строки.

CREATE OR REPLACE FUNCTION SPLIT_STRING (INPUT VARCHAR(8000), DELIMITER CHAR(1) DEFAULT ',')
RETURNS TABLE (str VARCHAR(8000))
SPECIFIC SPLIT_STRING
LANGUAGE SQL
DETERMINISTIC
NO EXTERNAL ACTION
return
select str
from xmltable('for $id in tokenize($s, $p) return <i>{string($id)}</i>' 
passing 
  --INPUT as "s"
  COALESCE(INPUT, CAST(RAISE_ERROR('70001', 'INVALID INPUT') AS VARCHAR(8000))) as "s"
, DELIMITER as "p"
columns 
  str varchar(8000) path '.'
) t;