MYSQL 启动问题

1、日志中出现  [ERROR] InnoDB: The Auto-extending innodb_system data file './ibdata1' is of a different size 640 pages (rounded down to MB) than specified in the .cnf file: initial 768 pages, max 0 (relevant if non-zero) pages! 有类似错误
   解决方案：在/etc/my.cnf 中修改或增加 innodb_data_file_path=ibdata1:10M:autoextend  计算方式：640页*16K/页 / 1024K/M = 10M
   
2、mysql.user table is damaged. Please run mysql_upgrade.
   解决方案：删除data 目录下的所有东西，使用 mysqld --initialize --user=mysql 命令初始化系统，保证系统能正常启动。
   
3、mysql登录及密码修改
   出现 error: 'Access denied for user 'root'@'localhost' (using password: YES)' 提示不能正常登录
   解决方案：
   安全启动mysql

mysqld_safe --user=mysql --skip-grant-tables --skip-networking &

mysql

mysql> update user set authentication_string=PASSWORD('root') where user='root';
Query OK, 1 row affected, 1 warning (0.04 sec)
Rows matched: 1  Changed: 1  Warnings: 1

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
修改成功

重新启动mysql也成功

mysql登录后，提示修改密码

mysql> show databases;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql> set PASSWORD=Password('root');
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> alter user root@localhost PASSWORD EXPIRE NEVER;
Query OK, 0 rows affected (0.00 sec)

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.01 sec)

密码修改成功，密码也不提示过期了。