Linux下安装MariaDB官方文档：https://mariadb.com/kb/en/library/yum/
5.7版本的官方介绍：https://www.w3cschool.cn/mysql/t9mdhf21.html
一、介绍
CentOS 6 或早期的版本中提供的是 MySQL 的服务器/客户端安装包，但 CentOS 7 已使用了 MariaDB 替代了默认的 MySQL。MariaDB数据库管理系统是MySQL的一个分支，主要由开源社区在维护，采用GPL授权许可 MariaDB的目的是完全兼容MySQL，包括API和命令行，使之能轻松成为MySQL的代替品。
我们为了需要，还是要在系统中安装MySQL，而且MySQL安装完成之后可以直接覆盖掉MariaDB。
查看MariaDB：
rpm -qa | grep mariadb注：这里我们不用卸载，等会覆盖安装即可。
二、安装
1 . 下载并安装MySQL官方的 Yum Repository https://dev.mysql.com/downloads/repo/yum/
[root@localhost ~]# wget http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
注：上面下载的版本为 5.7.25
2. 直接用yum安装
[root@localhost ~]# yum -y install mysql57-community-release-el7-10.noarch.rpm
3. 安装MySQL服务器
[root@localhost ~]# yum -y install mysql-community-server
安装完成后就会覆盖掉之前的mariadb
三、对mysql 进行设置
1. 启动MySQL
[root@localhost ~]# service mysqld start
2. 查看 MySQL状态
[root@localhost ~]# service mysqld status
3. 在日志文件中找到MySQLroot用户的密码
[root@localhost ~]#grep "password" /var/log/mysqld.log
4. 登录
[root@localhost ~]# mysql -u root -puykmo,U1+=Jw
5. 修改密码
新密码设置的时候如果设置的过于简单会报错，你要对数据库进行操作必须重新设置密码才可以。
原因是因为MySQL有密码设置的规范，具体是与validate_password_policy的值有关：
设置密码可以设置的很简单：
mysql> set global validate_password_policy=0;
mysql> set global validate_password_length=1;
设置密码：
mysql> SET PASSWORD=PASSWORD('修改为你的密码');
6. 卸载掉Yum Repository
因为安装了Yum Repository，以后每次yum操作都会自动更新，需要把这个卸载掉。
退出mysql:
mysql> quit;
卸载：
[root@localhost ~]# yum -y remove mysql57-community-release-el7-10.noarch
三、设置mysql 远程访问
1．显示数据库
mysql>show databases;
2．使用mysql数据库
mysql>use mysql;
4．展示mysql数据库中的所有表
mysql>show tables;
5．展示user表的结构
mysql>desc user;
6．查询user表
mysql>select User, Host from user;
注：host 表中都是只允许本机登录，我们需要修改任何机器都可以登录。
7．修改user表，把Host表内容修改为%
mysql>update user set host='%' where host='localhost';
8．删除root用户的其他host
mysql>delete from user where not (User='root' and Host='%');
9．查看是否成功
mysql>select User, Host from user;
注：这里的删除语句的写法根据实际的情况，只留下我们修改的这一条记录，如果把所有的记录都删除了需要通过跳过权限检查重新设置密码等。
10．刷新
mysql>flush privileges;
四、配置
[root@iZwz91s3dutue9omnmpihwZ mysql]# cat /etc/my.cnf
# 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增加如下信息，创建数据库的时候就不出现乱码了
[mysqld]
character-set-server=utf8
collation-server=utf8_general_ci
直接替换
[client]
port=3306
socket=/var/lib/mysql/mysql.sock
#1、添加客户端字符集
default-character-set=utf8
[mysqld]
port=3306
#2、增加
character_set_server=utf8
character_set_client=utf8
collation-server=utf8_general_ci
socket=/var/lib/mysql/mysql.sock
skip-locking
key_buffer_size = 384M
max_allowed_packet = 1M
table_open_cache = 512
#排序缓冲区的大小
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 8M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size = 32M
thread_concurrency = 8
log-bin=mysql-bin
server-id = 1
datadir=/var/lib/mysql
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[mysqldump]
quick
max_allowed_packet = 16M
[mysql]
no-auto-rehash
#3、增加
default-character-set=utf8
[myisamchk]
key_buffer_size = 256M
sort_buffer_size = 256M
read_buffer = 2M
write_buffer = 2M
[mysqlhotcopy]
interactive-timeout5.1.73 有一个配置模板 /usr/share/mysql/my-huge.cnf ，但是在 5.7.25 我没有找该模板。
# Example MySQL config file for very large systems.
#
# This is for a large system with memory of 1G-2G where the system runs mainly
# MySQL.
#
# MySQL programs look for option files in a set of
# locations which depend on the deployment platform.
# You can copy this option file to one of those
# locations. For information about these locations, see:
# http://dev.mysql.com/doc/mysql/en/option-files.html
#
# In this file, you can use all long options that a program supports.
# If you want to know which options a program supports, run the program
# with the "--help" option.
# The following options will be passed to all MySQL clients
[client]
#password = your_password
port = 3306
socket = /var/lib/mysql/mysql.sock
# Here follows entries for some specific programs
# The MySQL server
[mysqld]
port = 3306
socket = /var/lib/mysql/mysql.sock
skip-locking
key_buffer_size = 384M
max_allowed_packet = 1M
table_open_cache = 512
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 8M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size = 32M
# Try number of CPU's*2 for thread_concurrency
thread_concurrency = 8
# Don't listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
# All interaction with mysqld must be made via Unix sockets or named pipes.
# Note that using this option without enabling named pipes on Windows
# (via the "enable-named-pipe" option) will render mysqld useless!
#
#skip-networking
# Replication Master Server (default)
# binary logging is required for replication
log-bin=mysql-bin
# required unique id between 1 and 2^32 - 1
# defaults to 1 if master-host is not set
# but will not function as a master if omitted
server-id = 1
# Replication Slave (comment out master section to use this)
#
# To configure this host as a replication slave, you can choose between
# two methods :
#
# 1) Use the CHANGE MASTER TO command (fully described in our manual) -
# the syntax is:
#
# CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,
# MASTER_USER=<user>, MASTER_PASSWORD=<password> ;
#
# where you replace <host>, <user>, <password> by quoted strings and
# <port> by the master's port number (3306 by default).
#
# Example:
#
# CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,
# MASTER_USER='joe', MASTER_PASSWORD='secret';
#
# OR
#
# 2) Set the variables below. However, in case you choose this method, then
# start replication for the first time (even unsuccessfully, for example
# if you mistyped the password in master-password and the slave fails to
# connect), the slave will create a master.info file, and any later
# change in this file to the variables' values below will be ignored and
# overridden by the content of the master.info file, unless you shutdown
# the slave server, delete master.info and restart the slaver server.
# For that reason, you may want to leave the lines below untouched
# (commented) and instead use CHANGE MASTER TO (see above)
#
# required unique id between 2 and 2^32 - 1
# (and different from the master)
# defaults to 2 if master-host is set
# but will not function as a slave if omitted
#server-id = 2
#
# The replication master for this slave - required
#master-host = <hostname>
#
# The username the slave will use for authentication when connecting
# to the master - required
#master-user = <username>
#
# The password the slave will authenticate with when connecting to
# the master - required
#master-password = <password>
#
# The port the master is listening on.
# optional - defaults to 3306
#master-port = <port>
#
# binary logging - not required for slaves, but recommended
#log-bin=mysql-bin
#
# binary logging format - mixed recommended
#binlog_format=mixed
# Uncomment the following if you are using InnoDB tables
#innodb_data_home_dir = /var/lib/mysql
#innodb_data_file_path = ibdata1:2000M;ibdata2:10M:autoextend
#innodb_log_group_home_dir = /var/lib/mysql
# You can set .._buffer_pool_size up to 50 - 80 %
# of RAM but beware of setting memory usage too high
#innodb_buffer_pool_size = 384M
#innodb_additional_mem_pool_size = 20M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size = 100M
#innodb_log_buffer_size = 8M
#innodb_flush_log_at_trx_commit = 1
#innodb_lock_wait_timeout = 50
[mysqldump]
quick
max_allowed_packet = 16M
[mysql]
no-auto-rehash
# Remove the next comment character if you are not familiar with SQL
#safe-updates
[myisamchk]
key_buffer_size = 256M
sort_buffer_size = 256M
read_buffer = 2M
write_buffer = 2M
[mysqlhotcopy]
interactive-timeout
