There is no need to create your own function, and quite frankly, it seems a waste of time when this can be done fairly easily with sql functions that already exist. Care must be taken to account for sloppy data entry.
Here is another way to accomplish your stated goal:
with name_list as
(select ' Parisi, Kenneth R' name from dual)
select name
-- There may be a space after the comma. This will strip an arbitrary
-- amount of whitespace from the first name, so we can easily extract
-- the first initial.
, substr(trim(substr(name, instr(name, ',') + 1)), 1, 1) AS first_init
-- a simple substring function, from the first character until the
-- last character before the comma.
, substr(trim(name), 1, instr(trim(name), ',') - 1) AS last_name
-- put together what we have done above to create the output field
, lower(substr(trim(substr(name, instr(name, ',') + 1)), 1, 1)) ||
lower(substr(trim(name), 1, instr(trim(name), ',') - 1)) AS init_plus_last
from name_list;
HTH,
Gabe