handle invalid dates in Illinois Secretary of State incorporation data

cast_dates.sql

create or replace function is_date(s varchar) returns boolean as $$
/* function via https://stackoverflow.com/a/25374982 */
begin
  perform s::date;
  return true;
exception when others then
  return false;
end;
$$ language plpgsql;

begin;
update ilsos_corps_llc_master
set date_status_date = CASE WHEN is_date(status_date) THEN status_date::date ELSE null END;
commit;
rollback;