Centos7.4安装并配置Mysql5.7

[root@localhost~]#wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm[/code] 
安装mysql源

[root@localhost~]# yum localinstall mysql57-community-release-el7-8.noarch.rpm
提示【Is this ok [y/d/N]: y  输入y回车】
检查MySQL源是否安装成功
[root@localhost ~]# yum repolist enabled | grep “mysql.-community.”


2、安装MySQL

[root@localhost ~]# yum install mysql-community-server


注意：安装过程中提示【Is this ok [y/d/N]: y  输入y回车】

出现以下表示安装成功：

Replaced:
mariadb-libs.x86_64 1:5.5.56-2.el7

Complete!


3、启动MySQL服务

[root@localhost ~]# systemctl start mysqld
查看MySQL的启动状态
[root@localhost ~]# systemctl status mysqld


4.开机启动

[root@localhost ~]# systemctl enable mysqld
[root@localhost ~]# systemctl daemon-reload


查看mysql下root账号的默认密码

mysql5.7安装完成之后，在/var/log/mysqld.log文件中给root生成了一个默认密码。通过下面的方式找到root默认密码，然后登录mysql。

命令：grep ‘temporary password’ /var/log/mysqld.log

[root@localhost /]# grep 'temporary password' /var/log/mysqld.log
2017-10-17T08:07:03.797098Z 1 [Note] A temporary password is generated for root@localhost: 3prjY9ktM,eL
[root@localhost /]#
默认的密码是：3prjY9ktM,eL


修改配置文件

6.1. 默认配置文件路径

配置文件：/etc/my.cnf

日志文件：/var/log//var/log/mysqld.log

服务启动脚本：/usr/lib/systemd/system/mysqld.service

socket文件：/var/run/mysqld/mysqld.pid

6.2. 修改my.cnf文件

6.2.1. 修改密码策略

mysql的密码策略分为三种：

0或LOW：Length

1或MEDIUM：Length; numeric, lowercase/uppercase, and special characters

2或STRONG：Length; numeric, lowercase/uppercase, and special characters; dictionary file

在my.cnf文件中增加如下设置

如果不需要密码策略，禁用密码策略
validate_password = off

密码选择策略 0-LOW，1-MEDIUM，2-STRONG需要提供密码字典文件
validate_password_policy = 0

6.2.2. 修改字符编码为utf8

在[mysqld]下增加如下配置

character_set_server = utf8

init_connect = ‘SET NAMES utf8’

例：
[root@localhost /]# cd /etc/
[root@localhost etc]# vi my.cnf
validate_password = off# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html 
[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
validate_password = off  #设置禁用密码策略

character_set_server = utf8  #修改字符编码为utf8
init_connect = 'SET NAMES utf8'


6.2.3. 保存my.cnf并重启mysql服务是配置生效

命令：systemctl restart mysqld

登录mysql

命令：mysql -uroot -p

输入密码：默认为刚才查到的密码”3prjY9ktM,eL”

[root@localhost etc]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.20

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>


修改密码

命令：ALTER USER ‘root’@’localhost’ IDENTIFIED BY ‘12345678’;

或命令：set password for ‘root’@’localhost’=password(‘12345678’);

说明：

1. 如果之前没有设置密码策略，则密码12345678则不会通过验证，密码修改会失败

密码修改不成功时则部分功能也无法使用，例如查看密码策略 show variables like ‘%password%’;

查看密码策略

命令：show variables like ‘%password%’;

此处为 validate_password = off 设置后的结果

查看字符编码

命令：show variables like ‘%character%’;

添加远程账户

命令：GRANT ALL PRIVILEGES ON . TO ‘root’@’%’ IDENTIFIED BY ‘12345678’ WITH GRANT OPTION;

命令：FLUSH PRIVILEGES; 使设置生效

如果你想允许用户myuser从ip为192.168.0.107的主机连接到mysql服务器，并使用mypassword作为密码

GRANT ALL PRIVILEGES ON . TO ‘root’@’192.168.59.129’ IDENTIFIED BY ‘12345678’ WITH GRANT OPTION;

FLUSH PRIVILEGES;

至此，可以远程连接并操作数据库啦！

7.退出Mysql命令

quit或者exit退出mysql

8.service iptables status可以查看到iptables服务的当前状态。

但是即使服务运行了,防火墙也不一定起作用,你还得看防火墙规则的设置 iptables  -L

在此说一下关于启动和关闭防火墙的命令:

1) 重启后生效

开启： chkconfig iptables on

关闭： chkconfig iptables off

2) 即时生效，重启后失效

开启： service iptables start

关闭： service iptables stop

连接测试提示：2003 can’t connect to mysql server on ‘xxx.xxx.xxx.xxx’(10038)

解决办法：

centos查询端口是不是开放的
firewall-cmd –permanent –query-port=3306/tcp

添加对外开放端口
firewall-cmd –permanent –add-port=3306/tcp

重启防火墙
firewall-cmd –reload