MySQL基础
一、安装与配置
1、安装
yum install -y mysql-server.x86_64
2、MySQL安装完成后，启动报错，查看MySQL的状态，发现是3306端口被占用
[root@iZ56kkvaq4nlfhZ etc]# systemctl status mysqld.service
● mysqld.service - MySQL 8.0 database server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Tue 2023-09-12 18:58:37 CST; 10s ago
Process: 655712 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=0/SUCCESS)
Process: 655672 ExecStart=/usr/libexec/mysqld --basedir=/usr (code=exited, status=1/FAILURE)
Process: 655635 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (code=exited, status=0/SUCCESS)
Process: 655610 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/SUCCESS)
Main PID: 655672 (code=exited, status=1/FAILURE)
Status: "Server startup in progress"
Error: 98 (Address already in use)
Sep 12 18:58:34 iZ56kkvaq4nlfhZ systemd[1]: Starting MySQL 8.0 database server...
Sep 12 18:58:37 iZ56kkvaq4nlfhZ systemd[1]: mysqld.service: Main process exited, code=exited, status=1/FAILURE
Sep 12 18:58:37 iZ56kkvaq4nlfhZ systemd[1]: mysqld.service: Failed with result 'exit-code'.
Sep 12 18:58:37 iZ56kkvaq4nlfhZ systemd[1]: Failed to start MySQL 8.0 database server.
[root@iZ56kkvaq4nlfhZ etc]#
此时，可以查询是谁占用了3306，然后把占用进程kill掉，此处就可以使用命令kill 57039，但是我不想这么做，这个进程和我的一个服务有关，不能杀
[root@iZ56kkvaq4nlfhZ etc]# lsof -i :3306
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 57039 www 35u IPv6 149967 0t0 TCP *:mysql (LISTEN)
[root@iZ56kkvaq4nlfhZ etc]# netstat -anp | grep :3306
tcp6 0 0 :::3306 :::* LISTEN 57039/mysqld
于是，我选择修改MySQL的启动端口，将启动端口修改为3307，编辑下面的配置文件
vim /etc/my.cnf.d/mysql-server.cnf
添加一行内容，如下：
port=3307
此时配置文件就变成了：
[root@iZ56kkvaq4nlfhZ ~]# cat /etc/my.cnf.d/mysql-server.cnf
#
# This group are read by MySQL server.
# Use it for options that only the server (but not clients) should see
#
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/en/server-configuration-defaults.html
# 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 mysqld according to the
# instructions in http://fedoraproject.org/wiki/Systemd
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
port=3307 # 添加这一行，端口修改为3307
[root@iZ56kkvaq4nlfhZ ~]#
然后重启MySQL，就可以正常启动了
[root@iZ56kkvaq4nlfhZ etc]# systemctl restart mysqld.service
[root@iZ56kkvaq4nlfhZ etc]# systemctl status mysqld.service
● mysqld.service - MySQL 8.0 database server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; vendor prese> Active: active (running) since Tue 2023-09-12 19:09:51 CST; 16min ago
Process: 655712 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=> Process: 656204 ExecStartPost=/usr/libexec/mysql-check-upgrade (code=exited, st> Process: 656122 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (> Process: 656097 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, stat> Main PID: 656159 (mysqld)
Status: "Server is operational"
Tasks: 37 (limit: 10836)
Memory: 354.7M
CGroup: /system.slice/mysqld.service
└─656159 /usr/libexec/mysqld --basedir=/usr
Sep 12 19:09:50 iZ56kkvaq4nlfhZ systemd[1]: Starting MySQL 8.0 database server...
Sep 12 19:09:51 iZ56kkvaq4nlfhZ systemd[1]: Started MySQL 8.0 database server.
修改MySQL的密码，修改密码之后，再登录MySQL需要使用密码。
mysql # 进入MySQL命令行
# MySQL的用户名密码存储在这个数据库中，修改密码，必须使用这个数据库
mysql> use mysql;
# 查看数据库中的用户
mysql> select user,host from mysql.user;
+------------------+-----------+
| user | host |
+------------------+-----------+
| mysql.infoschema | localhost |
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
+------------------+-----------+
4 rows in set (0.00 sec)
# 修改'root'@'localhost'的密码
mysql> alter user 'root'@'localhost' identified with mysql_native_password by '12345';
Query OK, 0 rows affected (0.01 sec)
# 刷新权限
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql>
# 此时端口开放3307
mysql> show variables like '%port%' ;
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| admin_port | 33062 |
| large_files_support | ON |
| mysqlx_port | 33060 |
| mysqlx_port_open_timeout | 0 |
| port | 3307 |
| report_host | |
| report_password | |
| report_port | 3307 |
| report_user | |
| require_secure_transport | OFF |
+--------------------------+-------+
10 rows in set (0.01 sec)
mysql> exit
Bye
设置MySQL监听所有IP，更改配置文件后重启MySQL
[root@iZ56kkvaq4nlfhZ etc]# vim /etc/my.cnf.d/mysql-server.cnf
[root@iZ56kkvaq4nlfhZ etc]# cat /etc/my.cnf.d/mysql-server.cnf
#
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
port=3307
bind-address=0.0.0.0 # 添加这一行
[root@iZ56kkvaq4nlfhZ etc]#
[root@iZ56kkvaq4nlfhZ etc]# systemctl restart mysqld.service
[root@iZ56kkvaq4nlfhZ etc]# systemctl status mysqld.service
● mysqld.service - MySQL 8.0 database server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; vendor preset: disabled)
Active: active (running) since Tue 2023-09-12 20:56:18 CST; 11s ago
Process: 657283 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=0/SUCCESS)
Process: 657493 ExecStartPost=/usr/libexec/mysql-check-upgrade (code=exited, status=0/SUCCESS)
Process: 657411 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (code=exited, status=0/SUCCESS)
Process: 657385 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/SUCCESS)
Main PID: 657448 (mysqld)
Status: "Server is operational"
Tasks: 38 (limit: 10836)
Memory: 356.1M
CGroup: /system.slice/mysqld.service
└─657448 /usr/libexec/mysqld --basedir=/usr
Sep 12 20:56:17 iZ56kkvaq4nlfhZ systemd[1]: Starting MySQL 8.0 database server...
Sep 12 20:56:18 iZ56kkvaq4nlfhZ systemd[1]: Started MySQL 8.0 database server.
[root@iZ56kkvaq4nlfhZ etc]#
创建一个可以远程连接的root用户
CREATE USER 'root'@'%' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;
FLUSH PRIVILEGES;