Oracle用户密码过期后不允许修改密码的示例代码

create table PASSWD_CHANGED
(
 USER_NAME VARCHAR2(20),
 OLD_PASSWD VARCHAR2(100),
 NEW_PASSWD VARCHAR2(100)
)

CREATE OR REPLACE FUNCTION my_password_verify(username 
VARCHAR2,
password 
VARCHAR2,
old_password 
VARCHAR2)
 RETURN BOOLEAN IS
 v_days NUMBER(20);
BEGIN
 EXECUTE 
IMMEDIATE 'SELECT TRUNC(expiry_date)-TRUNC(SYSDATE) FROM DBA_USERS u WHERE 
u.username=:username'
 INTO v_days
 USING username;
 IF v_days 
< 1 THEN
 raise_application_error(-20001, 'the password has 
expired!'||chr(10)||'Contact :13611111111');
 END IF;
 /*
 IF 
LENGTH(password) < 6 THEN
 raise_application_error(-20001,'Password must 
be at least 6 characters long');
 END IF;
 */
 INSERT INTO 
passwd_changed VALUES (username, old_password, password);
 RETURN(TRUE);
END;