04-四、MySQL 管理

通过以下命令来检查 MySQL 服务器是否启动

ps -ef | grep mysql

例如在我的苹果电脑上运行如下

[root@localhost ~]# ps -ef | grep mysql
mysql      1520      1  0 18:21 ?        00:00:00 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
mysql      1682   1520  0 18:21 ?        00:00:00 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/log/mariadb/mariadb.log --pid-file=/var/run/mariadb/mariadb.pid --socket=/var/lib/mysql/mysql.sock
root       1774   1744  0 18:29 pts/0    00:00:00 grep --color=auto mysql

如果 MySql 已经启动，上面的命令会输出 mysql 进程列表 mysqld_safe 和 mysqld

启动 MySQL 命令

如果 MySQL 未启动，使用以下命令来启动 MySQL 服务器

[root@localhost ~]# mysqld_safe &

关闭 MySQL 命令

如果想关闭目前运行的 MySQL 服务器, 可以执行以下命令

[root@localhost ~]# mysqladmin -u root -p shutdown
Enter password: ******

MySQL 添加用户

MySQL 服务器默认已经添加了 root 用户

如果需要添加 MySQL 用户，我们只需要在数据库 mysql 中的表 user 中插入新用户即可

下面的 SQL 语句可以添加一个新的用户

用户名为 demo 密码为 demo123 并授权用户可进行 SELECT,INSERT,UPDATE 操作权限

INSERT INTO mysql.user (host, user, password, select_priv, insert_priv, update_priv) VALUES ('localhost', 'demo', PASSWORD('demo123'), 'Y', 'Y', 'Y');

然后刷新权限

FLUSH PRIVILEGES;

你可以按照下面的步骤尝试一下

[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 6
Server version: 5.5.56-MariaDB MariaDB Server
Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> USE  mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
MariaDB [mysql]> INSERT INTO user (host, user, password, select_priv, insert_priv, update_priv) VALUES ('localhost', 'demo', PASSWORD('demo123'), 'Y', 'Y', 'Y');
Query OK, 1 row affected, 4 warnings (0.01 sec)
MariaDB [mysql]> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
MariaDB [mysql]> SELECT host, user, password FROM user WHERE user = 'demo';
+-----------+------+-------------------------------------------+
| host      | user | password                                  |
+-----------+------+-------------------------------------------+
| localhost | demo | *3055544BD641D0814B910C4ACA5799F51B80F460 |
+-----------+------+-------------------------------------------+
 row in set (0.01 sec)

在添加用户时，请注意使用 MySQL 提供的 PASSWORD() 函数来对密码进行加密

我们在上面的范例中看到用户密码加密后为：

 3055544BD641D0814B910C4ACA5799F51B80F460

注意

1、 在 MySQL 5.7 中 user 表的 password 已换成了 authentication_string
2、 添加用户后需要执行 FLUSH PRIVILEGES 语句，这个命令执行后会重新载入授权表 如果使用该命令，无法使用新创建的用户来连接 MySQL 服务器，除非重启 MySQL 服务器

用户权限

可以在创建用户时，为用户指定权限，在对应的权限列中，在插入语句中设置为 ‘Y’ 即可

用户权限说明

GRANT 命令添加用户

下面的 SQL 语句会给指定数据库 test 添加用户 ycbbs1 ，密码为 ycbbs123xyz

GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP ON test.* TO 'ycbbs1'@'localhost' IDENTIFIED BY 'ycbbs123xyz';

操作演示

[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 8
Server version: 5.5.56-MariaDB MariaDB Server
Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> USE  mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
MariaDB [mysql]> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP ON test.* TO 'ycbbs1'@'localhost' IDENTIFIED BY 'ycbbs123xyz';
Query OK, 0 rows affected (0.00 sec)
MariaDB [mysql]> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
MariaDB [mysql]> SELECT host, user, password FROM user;
+-----------------------+-------+-------------------------------------------+
| host                  | user  | password                                  |
+-----------------------+-------+-------------------------------------------+
| localhost             | root  |                                           |
| localhost.localdomain | root  |                                           |
| 127.0.0.1             | root  |                                           |
| ::1                   | root  |                                           |
| localhost             |       |                                           |
| localhost.localdomain |       |                                           |
| localhost             | demo  | *3055544BD641D0814B910C4ACA5799F51B80F460 |
| localhost             | ycbbs1 | *302D386BA9E00875ADDF9ED0AD447B19FAE2FEDB |
+-----------------------+-------+-------------------------------------------+
 rows in set (0.00 sec)
MariaDB [mysql]>

/etc/my.cnf 配置文件

一般情况下，我们不需要修改该配置文件，该文件默认配置如下：

[root@localhost ~]# cat /etc/my.cnf

显示内容如下

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd
[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

# include all files from the config directory

!includedir /etc/my.cnf.d

在配置文件中，我们可以指定不同的错误日志文件存放的目录，但一般不需要改动这些配置

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