作者：耿进
爱可生 DBA 团队成员，负责公司 DMP 产品的运维和客户 MySQL 问题的解决。对数据库技术有着浓重的趣味。你见过凌晨四点 MySQL 的 error 吗？
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概述：
咱们先来重新认识一下 mysql.user 表中对于明码过期的字段，
mysql> use mysqlDatabase changedmysql> desc user;+------------------------+-----------------------------------+------+-----+-----------------------+-------+| Field | Type | Null | Key | Default | Extra |+------------------------+-----------------------------------+------+-----+-----------------------+-------+。。。。| password_expired | enum('N','Y') | NO | | N | || password_last_changed | timestamp | YES | | NULL | || password_lifetime | smallint(5) unsigned | YES | | NULL | |+------------------------+-----------------------------------+------+-----+-----------------------+-------+45 rows in set (0.01 sec)mysql> password_expired：从 MySQL 5.6.6 版本开始，增加了 password_expired 性能，它容许设置用户的过期工夫。
password_last_changed：明码最初一次批改的工夫。
password_lifetime：该用户明码的生存工夫，默认值为 NULL，除非手动批改此用户明码过期机制，否则都是 NULL。
另外解释一个参数：
default_password_lifetime：从 MySQL 5.7.4 版本开始，此全局变量能够设置一个全局的主动明码过期策略。
测试：
一、password_expired：手动设置过期
1.设置明码永不过期
mysql> grant all on *.* to test@'localhost' identified by '123';Query OK, 0 rows affected, 2 warnings (0.03 sec)mysql> select User,password_last_changed,password_lifetime,password_expired from mysql.user;+---------------+-----------------------+-------------------+------------------+| User | password_last_changed | password_lifetime | password_expired |+---------------+-----------------------+-------------------+------------------+| root | 2021-03-31 14:11:10 | NULL | N || mysql.session | 2021-03-31 14:11:06 | NULL | N || mysql.sys | 2021-03-31 14:11:06 | NULL | N || root | 2021-03-31 14:11:10 | NULL | N || universe_op | 2021-03-31 14:11:10 | NULL | N || kobe | 2021-04-01 16:45:20 | NULL | N | || test | 2021-04-16 17:30:18 | NULL | N |+---------------+-----------------------+-------------------+------------------+7 rows in set (0.00 sec)mysql> ALTER USER 'test'@'localhost' PASSWORD EXPIRE NEVER;Query OK, 0 rows affected (0.00 sec)mysql> mysql> select User,password_last_changed,password_lifetime,password_expired from mysql.user;+---------------+-----------------------+-------------------+------------------+| User | password_last_changed | password_lifetime | password_expired |+---------------+-----------------------+-------------------+------------------+| root | 2021-03-31 14:11:10 | NULL | N || mysql.session | 2021-03-31 14:11:06 | NULL | N || mysql.sys | 2021-03-31 14:11:06 | NULL | N || root | 2021-03-31 14:11:10 | NULL | N || universe_op | 2021-03-31 14:11:10 | NULL | N || kobe | 2021-04-01 16:45:20 | NULL | N | || test | 2021-04-16 17:30:18 | 0 | N |+---------------+-----------------------+-------------------+------------------+7 rows in set (0.00 sec)mysql>注：如果该参数设置为0，即示意明码永不过期。2.手动设置该用户明码为 30 day（它会主动笼罩明码过期的全局策略）
mysql> ALTER USER 'test'@'localhost' PASSWORD EXPIRE INTERVAL 30 DAY;Query OK, 0 rows affected (0.01 sec)mysql> select User,password_last_changed,password_lifetime,password_expired from mysql.user;+---------------+-----------------------+-------------------+------------------+| User | password_last_changed | password_lifetime | password_expired |+---------------+-----------------------+-------------------+------------------+| root | 2021-03-31 14:11:10 | NULL | N || mysql.session | 2021-03-31 14:11:06 | NULL | N || mysql.sys | 2021-03-31 14:11:06 | NULL | N || root | 2021-03-31 14:11:10 | NULL | N || universe_op | 2021-03-31 14:11:10 | NULL | N || kobe | 2021-04-01 16:45:20 | NULL | N | || test | 2021-04-16 17:30:18 | 30 | N |+---------------+-----------------------+-------------------+------------------+7 rows in set (0.00 sec)mysql> 3.设置明码立马过期
mysql> ALTER USER 'hhh'@'%' PASSWORD EXPIRE;Query OK, 0 rows affected (0.01 sec)mysql> mysql> select User,password_last_changed,password_lifetime,password_expired from mysql.user;+---------------+-----------------------+-------------------+------------------+| User | password_last_changed | password_lifetime | password_expired |+---------------+-----------------------+-------------------+------------------+| root | 2021-03-31 14:11:10 | NULL | N || mysql.session | 2021-03-31 14:11:06 | NULL | N || mysql.sys | 2021-03-31 14:11:06 | NULL | N || root | 2021-03-31 14:11:10 | NULL | N || universe_op | 2021-03-31 14:11:10 | NULL | N || kobe | 2021-04-01 16:45:20 | NULL | N | || test | 2021-04-16 17:30:18 | 30 | Y || gengjin | 2021-04-16 17:42:33 | NULL | N || hhh | 2021-04-16 18:00:32 | NULL | Y || kkk | 2021-04-16 18:26:06 | NULL | N |+---------------+-----------------------+-------------------+------------------+10 rows in set (0.00 sec)mysql> exitBye[root@manage01 ~]# /opt/mysql/base/5.7.25/bin/mysql -uhhh -p -S /opt/mysql/data/3306/mysqld.sockLogging to file '/mysqldata/mysql_3306/log/test.log'Enter password: Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 39469Server version: 5.7.25-logCopyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> show databases;ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.mysql> 二、default_password_lifetime：主动过期的机制
1.设置全局明码过期工夫：
#配置文件[mysqld]default_password_lifetime=90or#命令行全局批改mysql> SET GLOBAL default_password_lifetime = 90;Query OK, 0 rows affected (0.00 sec)mysql>mysql> show variables like "default_password_lifetime";+---------------------------+-------+| Variable_name | Value |+---------------------------+-------+| default_password_lifetime | 90 |+---------------------------+-------+1 row in set (0.00 sec)mysql> 2.创立用户：
mysql> grant all on *.* to hhh@'%' identified by '123';Query OK, 0 rows affected, 1 warning (0.04 sec)mysql> select User,password_last_changed,password_lifetime,password_expired from mysql.user;+---------------+-----------------------+-------------------+------------------+| User | password_last_changed | password_lifetime | password_expired |+---------------+-----------------------+-------------------+------------------+| root | 2021-03-31 14:11:10 | NULL | N || mysql.session | 2021-03-31 14:11:06 | NULL | N || mysql.sys | 2021-03-31 14:11:06 | NULL | N || root | 2021-03-31 14:11:10 | NULL | N || universe_op | 2021-03-31 14:11:10 | NULL | N || kobe | 2021-04-01 16:45:20 | NULL | N | || test | 2021-04-16 17:30:18 | 30 | Y || gengjin | 2021-04-16 17:42:33 | NULL | N || hhh | 2021-04-16 18:00:32 | NULL | N |+---------------+-----------------------+-------------------+------------------+9 rows in set (0.00 sec)mysql> 注：很多人一看这个 password_lifetime 为什么没有变，不应该变成 90 吗，是不是 mysql 的 bug，其实不然。
顺便贴一个这个“bug”的地址：
https://bugs.mysql.com/bug.ph...
它的工作形式如下:
有一个全局零碎变量 default_password_lifetime，它为应用默认明码生存期的所有帐户指定策略。在零碎表中这将存储一个 NULL。NULL 值被用作一个标记，表明所波及的帐户没有每个用户明码的非凡生存期。通过 ALTER USER password EXPIRE NEVER(将列设置为0)或 ALTER USER password EXPIRE INTERVAL N DAY(将列设置为 N)设置每个用户的非凡明码生存期。
因而，没有设置特定明码生存期的所有用户的所有明码生存期都将追随全局变量的值。