一 centos7上面没有mysql，它的数据库名字叫做mariadb （自带 5.7版本）
一 centos7 安装mariadb
[root@localhost ~]#yum install mariadb-server -y
[root@localhost ~]#systemctl start mariadb.service
[root@localhost ~]#systemctl stop firewalld
[root@localhost ~]#setenforce 0
[root@localhost ~]#ss -natp |grep 3306 #数据库端口3306
LISTEN 0 50 *:3306 *:* users:(("mysqld",pid=2478,fd=14))
[root@localhost ~]#mysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.68-MariaDB MariaDB ServerCopyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MariaDB [(none)]>
[root@localhost ~]#mysql_secure_installation #初始化设置 先输入密码 一路回车 
[root@mcb-11-8 ~]#mysql_secure_installation NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDBSERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!In order to log into MariaDB to secure it, we'll need the current
password for the root user. If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.Enter current password for root (enter for none): #初次运行直接回车
OK, successfully used password, moving on...Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation.Set root password? [Y/n] y #输入y并回车或直接回车
New password: #输入密码
Re-enter new password: #再次输入密码
Password updated successfully!
Reloading privilege tables..... Success!By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them. This is intended only for testing, and to make the installation
go a bit smoother. You should remove them before moving into a
production environment.Remove anonymous users? [Y/n] #是否删除匿名用户，生产环境建议删除... Success!Normally, root should only be allowed to connect from 'localhost'. This
ensures that someone cannot guess at the root password from the network.Disallow root login remotely? [Y/n] y ... Success!By default, MariaDB comes with a database named 'test' that anyone can
access. This is also intended only for testing, and should be removed
before moving into a production environment.Remove test database and access to it? [Y/n] #- Dropping test database...... Success!- Removing privileges on test database...... Success!Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.Reload privilege tables now? [Y/n] #是否重新加载权限表，直接回车... Success!Cleaning up...All done! If you've completed all of the above steps, your MariaDB
installation should now be secure.Thanks for using MariaDB!
[root@mcb-11-8 ~]#
注意：一般不使用mariadb
二 使用yum安装mysql
tee /etc/yum.repos.d/mysql.repo <<EOF
[mysql57-community]
name=MySQL 5.7 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/x86_64/
enabled=1
gpgcheck=0
EOFcat >/etc/yum.repos.d/mysql.repo <<EOF
[mysql57-community]
name=MySQL 5.7 Community Server
baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/x86_64/
enabled=1
gpgcheck=0
EOF实操： 做一下快照，除去5.7.3版本
多行重定向写mysql.repo配置官网mysql的yum源
[root@mcb-11-5 ~]# tee /etc/yum.repos.d/mysql.repo <<EOF
> [mysql]
> name=mysql5.7
> baseurl=https://mirrors.tuna.tsinghua.edu.cn/mysql/yum/mysql-5.7-community-el7-x86_64/
> gpgcheck=0
> EOF
[mysql]
name=mysql5.7
baseurl=https://mirrors.tuna.tsinghua.edu.cn/mysql/yum/mysql-5.7-community-el7-x86_64/
gpgcheck=0
[root@mcb-11-5 ~]# cat /etc/yum.repos.d/mysql.repo
[mysql]
name=mysql5.7
baseurl=https://mirrors.tuna.tsinghua.edu.cn/mysql/yum/mysql-5.7-community-el7-x86_64/
gpgcheck=0
mysql修改密码：
数据库的建立
①登录数据库后输入 show databases; (注意分号结尾)表示查看所有数据库，如上是默认库截图
②show create database 库名；查看某个库信息，如下查看默认库sys信息
③create database 库名； 创建数据库XX，如下创建class库
④ use 库名；进入某个库，如下进入class库
[root@localhost ~]#cat >/etc/yum.repos.d/mysql.repo <<EOF
> [mysql57-community]
> name=MySQL 5.7 Community Server
> baseurl=http://repo.mysql.com/yum/mysql-5.7-community/el/7/x86_64/
> enabled=1
> gpgcheck=0
> EOF
#多行重定向写mysql.repo配置官网mysql的yum源
[root@localhost ~]#systemctl stop firewalld
[root@localhost ~]#setenforce 0
setenforce: SELinux is disabled
[root@localhost ~]#yum -y install mysql-community-server
#安装mysql数据库
[root@localhost ~]#systemctl start mysqld
[root@localhost ~]#ss -natp|grep 3306
LISTEN 0 80 :::3306 :::* users:(("mysqld",pid=40798,fd=21))
[root@localhost ~]#
[root@localhost ~]#grep password /var/log/mysqld.log
2024-03-14T06:12:39.069864Z 1 [Note] A temporary password is generated for root@localhost: 0!5Uj&*IrOiE
[root@mcb-11-5 ~]# mysql -u root -p'0!5Uj&*IrOiE'
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.44
#在/var/log/mysqld.log日志文件中过滤password关键字查看初始的登录密码，注意无前面的空格
2024-03-13T07:56:54.672419Z 1 [Note] A temporary password is generated for
#mysql -uroot -p'查到的随机密码'
#登录数据库，注意密码有特殊符号是使用引号#修改密码策略
set global validate_password_policy=0;
set global validate_password_length=1;
alter user root@'localhost' identified by 'abc123'; #修改数据库密码set global validate_password_policy=0;set global validate_password_length=1; #修改密码策略
alter user root@localhost identified by 'abc123';
#修改用户root@localhost的密码为abc123注意数据库的mysql语句需要以 ; 结尾才能执行成功
root@localhost和root@10.0.0.1是俩个用户。
quit; #退出数据库
mysql -uroot -p'abc123'
#使用新密码登录数据库成功，密码修改成功我们看到使用数据库，不能显示当前位置，还没有补全，打错命令还需要重新打，接下来我们就来优化mysql数据库吧
三 安装mycli 插件 客户端工具
mycli 和 mysql 都是客户端工具
[root@mcb-11-5 ~]#yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel libffi-devel
[root@mcb-11-5 ~]#mkdir /data/
[root@mcb-11-5 ~]#cd /data/
[root@mcb-11-5 data]#ls
[root@mcb-11-5 data]#rz -E
rz waiting to receive.
[root@mcb-11-5 data]#ls
Python-3.7.7_.tgz
[root@mcb-11-5 data]#tar xf Python-3.7.7_.tgz
[root@mcb-11-5 data]#ls
Python-3.7.7 Python-3.7.7_.tgz
[root@mcb-11-5 data]#cd Python-3.7.7/
[root@mcb-11-5 Python-3.7.7]#./configure --prefix=/usr/local/Python-3.7.7/
[root@mcb-11-5 Python-3.7.7]#yum install gcc -y
[root@mcb-11-5 Python-3.7.7]#./configure --prefix=/usr/local/Python-3.7.7/
[root@mcb-11-5 Python-3.7.7]#make -j 2
[root@mcb-11-5 Python-3.7.7]#make install
[root@mcb-11-5 Python-3.7.7]#ln -s /usr/local/Python-3.7.7/bin/python3.7 /usr/bin/python37
[root@mcb-11-5 Python-3.7.7]#ln -s /usr/local/Python-3.7.7/bin/pip3.7 /usr/bin/pip37
[root@mcb-11-5 Python-3.7.7]#pip37 install mycli -i http://mirrors.aliyun.com/pypi/simple --trusted-host mirrors.aliyun.com
[root@mcb-11-5 Python-3.7.7]#ln -s /usr/local/Python-3.7.7/bin/mycli /usr/bin/mycli
[root@mcb-11-5 Python-3.7.7]#mycli -uroot -pabc123
Connecting to socket /var/lib/mysql/mysql.sock, owned by user mysql
MySQL
mycli 1.27.0
Home: http://mycli.net
Bug tracker: https://github.com/dbcli/mycli/issues
Thanks to the contributor - François Pietka
MySQL root@(none):(none)> quit
Goodbye!
[root@mcb-11-5 Python-3.7.7]#
mycli 官网 点击就可进入MyCLI is a command line interface for MySQL, MariaDB, and Percona with auto-completion and syntax highlighting.四 进入配置文件 vim /etc/my.cnf 修改
[root@mcb-11-5 Python-3.7.7]# vim /etc/my.cnf
若启动不起来
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