centos安装Mysql版本5.7

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[root@vm-node1 ~]# cat /proc/cpuinfo | grep 'model name' |uniq
model name	: Intel(R) Core(TM) i9-10900 CPU @ 2.80GHz

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[root@base home]# rpm -qa|grep mysql
[root@base home]# rpm -qa|grep mariadb
mariadb-libs-5.5.56-2.el7.x86_64

移除，找到检测冲突，进行移除
yum remove mariadb-libs-5.5.56-2.el7.x86_64

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rpm -ivhg mysql-community-common-5.7.35-1.el7.x86_64.rpm 
rpm -ivhg mysql-community-libs-5.7.35-1.el7.x86_64.rpm
rpm -ivhg mysql-community-client-5.7.35-1.el7.x86_64.rpm
rpm -ivhg mysql-community-server-5.7.35-1.el7.x86_64.rpm

以上顺序有依赖关系，不要跨顺序安装

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[root@vm-node1 home]# systemctl start mysqld

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[root@vm-node1 home]# grep 'temporary password' /var/log/mysqld.log
2021-12-18T03:31:30.464157Z 1 [Note] A temporary password is generated for root@localhost: VIqgJb2Rr<vu
2021-12-18T04:03:06.784139Z 1 [Note] A temporary password is generated for root@localhost: l=ufaG7-Bx&c

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[root@vm-node1 home]# mysql -uroot -poKcftk:nl3x=
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 8
Server version: 8.0.26

Copyright (c) 2000, 2021, Oracle and/or its affiliates.

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>alter user user() identified by "!QAZ2wsx";
Query OK, 0 rows affected (0.02 sec)
exit

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mysql> 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
mysql> ALTER user 'root'@'localhost' IDENTIFIED BY 'Qaz.1234';
Query OK, 0 rows affected (0.00 sec)

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grant all privileges on *.* to 'username'@'%' identified by 'password' with grant option;

grant all privileges on *.* to 'root'@'%' identified by 'Qaz.1234' with grant option;
flush privileges;
quit;

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systemctl stop firewalld
或者
firewall-cmd --add-port=3306/tcp --permanent
firewall-cmd --reload

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[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

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[mysqld]
port=3306
# 设置3306端口
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

innodb_buffer_pool_size = 128M
# INNODB的一级缓存，默认是128M，在专用数据库服务器上，可以配置内存的80%。
lower_case_table_names = 1
# 是否支持数据库大小写敏感，默认为0，1表示不敏感，所以也是必须要配置
max_connections=1000
# 允许的最大连接数，默认为100，所以必须配置
# 实际起作用的最大值（实际最大可连接数）为16384，该参数在服务器资源够用的情况下应该尽量设置大，以满足多个客户端同时连接的需求。否则将会出现类似”Too many # connections”的错误。配置可以根据业务1000-10000。具体和业务规模，是否专用数据库服务器(CPU,内存)相关,查询密度。
# 该值配置大不会占用服务器系统资源。
max_connect_errors=100
# 允许连接失败的次数。这是为了防止有人从该主机试图攻击数据库系统
character-set-server=utf8mb4
# 服务端使用的字符集默认为UTF8
[client]
# 设置mysql客户端连接服务端时默认使用的端口
port=3306
default-character-set=utf8mb4

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rpm -qa|grep mysql
rpm -ev XXX
如果提示依赖包错误，则使用以下命令尝试
rpm -ev XXX --nodeps
检测是否有遗留文件未删除
find / -name mysql
rm -rf /var/lib/mysql
rm -rf /usr/bin/mysql
rm -rf /usr/lib64/mysql
rm -rf /usr/share/mysql
rm -rf /etc/selinux/targeted/active/modules/100/mysql
rm -rf /etc/selinux/targeted/tmp/modules/100/mysql

rm -rf /etc/my.cnf
#这样会删除原有mysql的数据，如果需要备份，首先进行备份