MySQL数据库root密码丢失后的找回

实验前准备:
1.环境
端口3306 该实例是生产环境,欲找回3306的 root密码
测试3307 测试时使用
2.开启 3306,3307 mysqld 服务

[[email protected] ~]# mysqld --defaults-file=/data/mysql/mysql3306/my.cnf &
[[email protected] ~]# mysqld --defaults-file=/data/mysql/mysql3307/my.cnf & 

两种方法:
一.使用 skip_grant_tables 参数

[[email protected] ~]# ps -ef|grep 3306|grep -v grep
mysql 947 365 0 19:00 pts/0 00:00:00 mysqld --defaults-file=/data/mysql/mysql3306/my.cnf
[[email protected] ~]# kill -9 947
[[email protected] ~]# mysqld --defaults-file=/data/mysql/mysql3306/my.cnf --skip_grant_tables &
[[email protected] ~]# mysql -S /tmp/mysql3306.sock

mysql> alter user user() identified by ‘zstzst‘;
ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
mysql> update mysql.user set authentication_string=password(‘zstzst3306‘) where host=‘localhost‘ and user=‘root‘;
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 1

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> shutdown;
Query OK, 0 rows affected (0.00 sec)

[[email protected] ~]# mysqld --defaults-file=/data/mysql/mysql3306/my.cnf &
[[email protected] ~]# mysql -S /tmp/mysql3306.sock -pzstzst3306 #登陆成功

这个方法需要重启MySQL服务,由于免密码登陆,所以再启动数据库时,最好也要加上参数 --skip__networking

二.拷贝修改user.*

3306 老密码是zstzst,假装遗忘,通过拷贝user*文件方式修改成zstzst3306
3307 password‘zstzst3307‘

[[email protected] ~]# mysql -S /tmp/mysql3306.sock -pzstzst3306
mysql> alter user [email protected] identified by ‘zstzst‘; #3306密码修改成 zstzst

[[email protected] ~]# ps -ef|grep mysqld|grep -v grep
mysql 1032 365 0 19:00 pts/0 00:00:00 mysqld --defaults-file=/data/mysql/mysql3307/my.cnf
mysql 3960 365 0 19:05 pts/0 00:00:00 mysqld --defaults-file=/data/mysql/mysql3306/my.cnf
[[email protected] ~]# kill -9 1032 #杀掉3307
[ro[email protected] ~]# \cp /data/mysql/mysql3306/data/mysql/user.frm /data/mysql/mysql3307/data/mysql/user.frm
[[email protected] ~]# \cp /data/mysql/mysql3306/data/mysql/user.MYD /data/mysql/mysql3307/data/mysql/user.MYD
[[email protected] ~]# \cp /data/mysql/mysql3306/data/mysql/user.MYI /data/mysql/mysql3307/data/mysql/user.MYI
[[email protected] ~]# mysqld --defaults-file=/data/mysql/mysql3307/my.cnf --skip_grant_tables & #这样不用重启生产库
[[email protected] ~]# mysql -S /tmp/mysql3307.sock

mysql> update mysql.user set authentication_string=password(‘zstzst3306‘) where host=‘localhost‘ and user=‘root‘;
Query OK, 0 rows affected, 1 warning (0.00 sec)
Rows matched: 1 Changed: 0 Warnings: 1

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

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

[[email protected] ~]# \cp /data/mysql/mysql3307/data/mysql/user.frm /data/mysql/mysql3306/data/mysql/user.frm
[[email protected] ~]# \cp /data/mysql/mysql3307/data/mysql/user.MYD /data/mysql/mysql3306/data/mysql/user.MYD
[[email protected] ~]# \cp /data/mysql/mysql3307/data/mysql/user.MYI /data/mysql/mysql3306/data/mysql/user.MYI
[[email protected] ~]# kill -HUP 3960
[[email protected] ~]# mysql -S /tmp/mysql3306.sock -pzstzst3306 #验证登陆成功

原文地址：https://www.cnblogs.com/bkwong/p/9264973.html