CREATE OR REPLACE 
FUNCTION get_greece_alphabet_py(p_Index NUMBER)
RETURN NUMBER IS
  v_greece_alphabet_list TGREECE_ALPHABET_LIST := TGREECE_ALPHABET_LIST(
    'a','b','g','d','e','z','e','th','i','k','l','m','n','x','o','p','r',
    's','t','u','ph','kh','ps','o'
  );
BEGIN
  IF (p_Index>0) AND (p_Index<95) THEN
    RETURN v_greece_alphabet_list(p_Index);
  ELSE
    RETURN '';
  END IF;
end get_greece_alphabet_py;

CREATE OR REPLACE 
FUNCTION get_greece_alphabet_py(p_Index NUMBER)
RETURN NUMBER IS
  type TGREECE_ALPHABET_LIST is table of varchar2(10);--你使用了集合類型，但沒有定義，定義下就可以了
  v_greece_alphabet_list TGREECE_ALPHABET_LIST := TGREECE_ALPHABET_LIST(
    'a','b','g','d','e','z','e','th','i','k','l','m','n','x','o','p','r',
    's','t','u','ph','kh','ps','o'
  );
BEGIN
  IF (p_Index>0) AND (p_Index<95) THEN
    RETURN v_greece_alphabet_list(p_Index);
  ELSE
    RETURN '';
  END IF;
end get_greece_alphabet_py;
/

------解决方案--------------------
SQL code

--可以
create or replace type TGREECE_ALPHABET_LIST is table of varchar2(10);
/
CREATE OR REPLACE 
FUNCTION get_greece_alphabet_py(p_Index NUMBER)
RETURN NUMBER IS
  v_greece_alphabet_list TGREECE_ALPHABET_LIST := TGREECE_ALPHABET_LIST(
    'a','b','g','d','e','z','e','th','i','k','l','m','n','x','o','p','r',
    's','t','u','ph','kh','ps','o'
  );
BEGIN
  IF (p_Index>0) AND (p_Index<95) THEN
    RETURN v_greece_alphabet_list(p_Index);
  ELSE
    RETURN '';
  END IF;
end get_greece_alphabet_py;
/