如何在PL/SQL中格式化数字？

DECLARE
    num NUMBER := 12345.67;
    formatted_num VARCHAR2(20);
BEGIN
    formatted_num := TO_CHAR(num, '999,999.99');
    DBMS_OUTPUT.PUT_LINE(formatted_num);
END;

DECLARE
    num NUMBER := 12345.67;
    integer_part NUMBER;
    decimal_part NUMBER;
    formatted_num VARCHAR2(20);
BEGIN
    integer_part := FLOOR(num);
    decimal_part := MOD(num, 1);
    formatted_num := TO_CHAR(integer_part, '99,999') || '.' || TO_CHAR(decimal_part, '0.00');
    DBMS_OUTPUT.PUT_LINE(formatted_num);
END;

CREATE OR REPLACE FUNCTION format_number(p_num NUMBER) RETURN VARCHAR2 IS
    integer_part NUMBER;
    decimal_part NUMBER;
    formatted_num VARCHAR2(20);
BEGIN
    integer_part := FLOOR(p_num);
    decimal_part := MOD(p_num, 1);
    formatted_num := TO_CHAR(integer_part, '99,999') || '.' || TO_CHAR(decimal_part, '0.00');
    RETURN formatted_num;
END;
/

-- 调用函数
DECLARE
    num NUMBER := 12345.67;
    formatted_num VARCHAR2(20);
BEGIN
    formatted_num := format_number(num);
    DBMS_OUTPUT.PUT_LINE(formatted_num);
END;