Oracle Function to get a specific field from a String contains fields characters delimited

Hi All

Today a simple function to extract a field from a String contains characters delimited fields.
I want use regexp_substr function but there are some problems for null fields to extract, so i develop this simple function.

CREATE OR REPLACE FUNCTION
  get_field (iString IN VARCHAR2, iSeparator IN VARCHAR2, field_num IN NUMBER)
RETURN VARCHAR2
IS
   oField VARCHAR2(1024);
   position_field NUMBER;
   position_field_start NUMBER;
   position_field_end NUMBER;
BEGIN

  IF field_num = 1 THEN
     position_field :=  INSTR(iString,iSeparator);
     IF position_field > 0 THEN
        SELECT SUBSTR(iString,1,INSTR(iString,iSeparator)-1) INTO oField FROM DUAL;
     ELSE
        oField := iString;
     END IF;
  ELSE
      position_field_start :=  INSTR(iString,iSeparator,1,field_num-1);
      position_field_end :=  INSTR(iString,iSeparator,1,field_num);

      IF position_field_start > 0 THEN
      
            IF position_field_end = 0 THEN
               position_field_end := length(iString)+1;
            END IF;
           SELECT SUBSTR(iString,position_field_start+1,position_field_end-position_field_start-1) INTO oField FROM DUAL;
      ELSE
         oField := null;
      END IF; 
  END IF;

  RETURN (oField);
END;

For example you have this string '10;12;34;233;12' delimited by ';' character and you wont get third field.
You can call this oracle function in this way :

SELECT GET_FIELD('10;12;34;233;12',';',3) FROM DUAL;

Results will be : '34'.

I hope can help someone with same problem.

Stay tuned