MySQL If you delete all the users how to do?
premise:
1, there is determined a database Close
2, is determined from a database and no master
Operating procedures:
1. Shut down the database
2, not to verify the landing approach (no password required)
3, enter a user authorization database in mysql database
4, or to insert data in the user table mysql
As follows:
[root@localhost ~]# mysql -uroot -p123
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
# This specifies the user can not login and password
[root@localhost ~]# service mariadb stop
# Stop the database
[root@localhost ~]# mysqld_safe --skip-grant-tables --skip-networking &
# Conduct free secret landing
MariaDB [(none)]> use mysql
Database changed
MariaDB [mysql]> GRANT ALL PRIVILEGES ON *.* TO root@localhost IDENTIFIED BY 'password' WITH GRANT OPTION;
Query OK, 0 rows affected (0.00 sec)
MariaDB [mysql]> select user, host from user;
+------+-----------+
| user | host |
+------+-----------+
| root | localhost |
+------+-----------+
1 row in set (0.00 sec)
The second method
What the user table columns If you use this method you need to know
| MariaDB [mysql]> desc user; +------------------------+-----------------------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +------------------------+-----------------------------------+------+-----+---------+-------+ | Host | char (60) | NO | PRI | | | | User | char(16) | NO | PRI | | | | Password | char(41) | NO | | | | | SELECT_priv | enum ( 'N', 'Y') | NO | | N | | | Insert_priv | enum('N','Y') | NO | | N | | | Update_priv | enum('N','Y') | NO | | N | | | Delete_priv | enum ( 'N', 'Y') | NO | | N | | | Create_priv | enum ( 'N', 'Y') | NO | | N | | | Drop_priv | enum('N','Y') | NO | | N | | | Reload_priv | enum ( 'N', 'Y') | NO | | N | | | Shutdown_priv | enum ( 'N', 'Y') | NO | | N | | | Process_priv | enum ( 'N', 'Y') | NO | | N | | | File_priv | enum ( 'N', 'Y') | NO | | N | | | Grant_priv | enum ( 'N', 'Y') | NO | | N | | | References_priv | enum ( 'N', 'Y') | NO | | N | | | Index_priv | enum ( 'N', 'Y') | NO | | N | | | Alter_priv | enum ( 'N', 'Y') | NO | | N | | | Show_db_priv | enum('N','Y') | NO | | N | | | Super_priv | enum ( 'N', 'Y') | NO | | N | | | Create_tmp_table_priv | enum('N','Y') | NO | | N | | | Lock_tables_priv | enum('N','Y') | NO | | N | | | Execute_priv | enum('N','Y') | NO | | N | | | Repl_slave_priv | enum('N','Y') | NO | | N | | | Repl_client_priv | enum('N','Y') | NO | | N | | | Create_view_priv | enum('N','Y') | NO | | N | | | Show_view_priv | enum('N','Y') | NO | | N | | | Create_routine_priv | enum('N','Y') | NO | | N | | | Alter_routine_priv | enum('N','Y') | NO | | N | | | Create_user_priv | enum('N','Y') | NO | | N | | | Event_priv | enum('N','Y') | NO | | N | | | Trigger_priv | enum('N','Y') | NO | | N | | | Create_tablespace_priv | enum('N','Y') | NO | | N | | | ssl_type | enum('','ANY','X509','SPECIFIED') | NO | | | | | ssl_cipher | blob | NO | | NULL | | | x509_issuer | blob | NO | | NULL | | | x509_subject | blob | NO | | NULL | | | max_questions | int(11) unsigned | NO | | 0 | | | max_updates | int(11) unsigned | NO | | 0 | | | max_connections | int(11) unsigned | NO | | 0 | | | max_user_connections | int(11) | NO | | 0 | | | plugin | char(64) | NO | | | | | authentication_string | text | NO | | NULL | | +------------------------+-----------------------------------+------+-----+---------+-------+ 42 rows in set (0.01 sec) |
#这里是user表中的字段，如果需要插入超级用户需要有所有的权力，即这里的列为Y
操作语句
MariaDB [(none)]> insert into mysql.user values('127.0.0.1','root',PASSWORD('123'),'Y','Y', 'Y', 'Y', 'Y', 'Y','Y', 'Y', 'Y', 'Y', 'Y','Y', 'Y', 'Y', 'Y', 'Y','Y', 'Y', 'Y', 'Y', 'Y','Y', 'Y', 'Y', 'Y', 'Y','Y', 'Y', 'Y','','','',0,0,0,0,'mysql_native_password','','N');
#重启数据库
MariaDB [mysql]> select user,host from user;
+------+-----------+
| user | host |
+------+-----------+
| root | 127.0.0.1 |
| root | localhost |
+------+-----------+
2 rows in set (0.00 sec)
mysql的连接
mysql命令是mysql自带的连接数据库工具，其本质是mysql客户端
常见参数有：
-u 指定用户
-p 指定密码
-h 指定IP地址用于远程连接
-S 指定soket文件
-e 指定使使用的sql语句
--protocol=name 指定连接方式
第三方工具
sqlyon、navtcat
mysqld_safe与mysqld区别
mysqld是mysql的守护进程。每次在使用mysql前必须先用它。mysqld是计算机进程，MySQL数据库服务器相关程序。
mysqld_safe
1. 检查系统和选项。
2. 检查MyISAM表。
3. 保持MySQL服务器窗口。
4. 启动并监视mysqld，如果因错误终止则重启。
5. 将mysqld的错误消息发送到数据目录中的host_name.err 文件。
6. 将mysqld_safe的屏幕输出发送到数据目录中的host_name.safe文件。
mysqld_safe的常用参数详解
| 参数 |
说明 |
| --skip-grant-tables |
跳过安全验证 |
| --skip-networking |
关闭tcp连接 |
| --datadir=path |
指定安装目录 |
| --basedir=path |
指定数据目录 |
| --defaults-file=path |
指定数据库配置目录 |
| --pid-file=path |
指定pid文件目录 |
| --socket=path |
指定socket文件 |
| --user=username |
指定启动用户 |
| --port=3306 |
指定端口 |
| --log-error |
指定错误日志目录 |
MySQL数据库启动流程
