Db2 11.1

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CREATE FUNCTION SPLITTER (input VARCHAR(4000), delimiter CHAR, part_number INTEGER)
      RETURNS VARCHAR(4000)
      LANGUAGE SQL
      READS SQL DATA
      NO EXTERNAL ACTION
      DETERMINISTIC
      RETURN 
      
with pos_info (first_pos, length) as (
select 
  case when part_number = 1 then 0
       else LOCATE_IN_STRING(input, delimiter,1, part_number-1, OCTETS)  
  end as first_pos, 

  case when part_number = 1 then LOCATE_IN_STRING(input, delimiter,1, part_number, OCTETS) - 1 
       when LOCATE_IN_STRING(input, delimiter,1, part_number, OCTETS) = 0
        and  LOCATE_IN_STRING(input, delimiter,1, part_number-1, OCTETS) = 0
       then 0
       when LOCATE_IN_STRING(input, delimiter,1, part_number, OCTETS) = 0
       then length(input) -  LOCATE_IN_STRING(input, '-',1, part_number - 1, OCTETS)
       else LOCATE_IN_STRING(input, delimiter,1, part_number, OCTETS) - LOCATE_IN_STRING(input, delimiter,1, part_number-1, OCTETS) - 1
  end as length
from sysibm.sysdummy1
)

select    
    substr(input, first_pos+1,length) as part
from pos_info;
    
select SPLITTER('HELLO-WORLD', '-', 1) from sysibm.sysdummy1;

1

HELLO

select SPLITTER('HELLO-WORLD', '-', 2) from sysibm.sysdummy1;

1

WORLD

select SPLITTER('HELLO-WORLD', '-', 3) from sysibm.sysdummy1;

1

select SPLITTER('CHG-FFH.', '-', 1) from sysibm.sysdummy1;

1

CHG

select SPLITTER('CHG-FFH.', '-', 2) from sysibm.sysdummy1;

1

FFH.