centos7使用的MariaDB，替代了早期版本默认的MySQL。MariaDB是MySQL的一个分支，由开源社区维护，采用GPL授权许可，且MariaDB完全贱人MySQL。
检查centos7下现有的MariaDB安装包：
[hadoop@hadoop01 ~]$ rpm -qa| grep mariadb
mariadb-libs-5.5.60-1.el7_5.x86_64
删除MariaDB安装包：
[hadoop@hadoop01 ~]$ su root
Password:
[root@hadoop01 hadoop]# rpm -e --nodeps mariadb-libs-5.5.60-1.el7_5.x86_64
下载mysql安装包：
mysql-8.0.17-1.el7.x86_64.rpm-bundle.tar
注：要对应各自centos的版本，我用的是centos7
检查是否安装其他mysql包：
rpm -qa | grep mysql
安装mysql：
rpm -ivh mysql-community-common-8.0.17-1.el7.x86_64.rpm
rpm -ivh mysql-community-libs-8.0.17-1.el7.x86_64.rpm
rpm -ivh mysql-community-client-8.0.17-1.el7.x86_64.rpm
rpm -ivh mysql-community-server-8.0.17-1.el7.x86_64.rpm
成功结果：
[root@hadoop01 hadoop]# rpm -ivh mysql-community-common-8.0.1
warning: mysql-community-common-8.0.17-1.el7.x86_64.rpm: Head
Preparing... #######################
Updating / installing...
1:mysql-community-common-8.0.17-1.e#######################
[root@hadoop01 hadoop]# rpm -ivh mysql-community-libs-8.0.17-
warning: mysql-community-libs-8.0.17-1.el7.x86_64.rpm: Header
Preparing... #######################
Updating / installing...
1:mysql-community-libs-8.0.17-1.el7#######################
[root@hadoop01 hadoop]# rpm -ivh mysql-community-client-8.0.1
warning: mysql-community-client-8.0.17-1.el7.x86_64.rpm: Head
Preparing... #######################
Updating / installing...
1:mysql-community-client-8.0.17-1.e#######################
[root@hadoop01 hadoop]# rpm -ivh mysql-community-server-8.0.1
warning: mysql-community-server-8.0.17-1.el7.x86_64.rpm: Head
Preparing... #######################
Updating / installing...
1:mysql-community-server-8.0.17-1.e#######################
mysql启动关闭状态：
[root@hadoop01 hadoop]# service mysqld start --启动
Redirecting to /bin/systemctl start mysqld.service
[root@hadoop01 hadoop]# service mysqld stop --关闭
Redirecting to /bin/systemctl stop mysqld.service
[root@hadoop01 hadoop]# service mysqld status --查看状态
Redirecting to /bin/systemctl status mysqld.service
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: inactive (dead) since Tue 2019-09-17 01:23:32 CST; 24s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 9334 ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 9247 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 9334 (code=exited, status=0/SUCCESS)
Status: "Server shutdown complete"
Sep 17 01:17:08 hadoop01 systemd[1]: Starting MySQL Server...
Sep 17 01:17:19 hadoop01 systemd[1]: Started MySQL Server.
Sep 17 01:23:30 hadoop01 systemd[1]: Stopping MySQL Server...
Sep 17 01:23:32 hadoop01 systemd[1]: Stopped MySQL Server.
首次登陆获取自动生成的临时密码：
[root@hadoop01 hadoop]# sudo grep 'temporary password' /var/log/mysqld.log
2019-09-16T17:17:17.183833Z 5 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: ?jeVxKndj40d
[root@hadoop01 hadoop]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 8
Server version: 8.0.17
Copyright (c) 2000, 2019, 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>
--到此成功登陆mysql，下面我们需要修改root账户的登陆密码才能进行数据库相关操作。
--修改密码命令：ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPassword'
创建授权删除查询新用户：
mysql> create user 'User'@'localhost' identified by 'User_123456'; --创建
Query OK, 0 rows affected (0.02 sec)
mysql> grant all privileges on *.* to 'User'@'localhost'; --授权
Query OK, 0 rows affected (0.02 sec)
mysql> drop user User@localhost; --删除
Query OK, 0 rows affected (0.01 sec)
mysql> select user,host from mysql.user;--查询
+------------------+-----------+
| user | host |
+------------------+-----------+
| mysql.infoschema | localhost |
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
+------------------+-----------+
4 rows in set (0.01 sec)
我们进行如下操作：
mysql> create user 'User'@'localhost' identified by 'User_123456';
Query OK, 0 rows affected (0.01 sec)
mysql> grant all privileges on *.* to 'User'@'localhost';
Query OK, 0 rows affected (0.01 sec)
mysql> create user 'User'@'%' identified by 'User_123456';
Query OK, 0 rows affected (0.01 sec)
mysql> grant all privileges on *.* to 'User'@'%';
Query OK, 0 rows affected (0.01 sec)
mysql> create user 'User'@'master' identified by 'User_123456';
Query OK, 0 rows affected (0.01 sec)
mysql> grant all privileges on *.* to 'User'@'master';
Query OK, 0 rows affected (0.02 sec)
mysql> select user,host from mysql.user;
+------------------+-----------+
| user | host |
+------------------+-----------+
| User | % |
| User | localhost |
| mysql.infoschema | localhost |
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
| User | master |
+------------------+-----------+
7 rows in set (0.00 sec)
mysql数据库的基本操作：
mysql> create database test_db;--创建数据库
Query OK, 1 row affected (0.01 sec)
mysql> show databases; --展示数据库
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test_db |
+--------------------+
5 rows in set (0.07 sec)
mysql> use test_db; --进入数据库
Database changed
mysql> create table myclass ( --创建数据表
-> id int(4) not null primary key auto_increment,
-> name char(20) not null,
-> sex int(4) not null default '0',
-> degree double(16,2));
Query OK, 0 rows affected, 3 warnings (0.04 sec)
mysql> insert into myclass values(0001,"Liu Qin Jiang",0,100.00); --插入数据
Query OK, 1 row affected (0.02 sec)
mysql> select * from myclass; -查询数据
+----+---------------+-----+--------+
| id | name | sex | degree |
+----+---------------+-----+--------+
| 1 | Liu Qin Jiang | 0 | 100.00 |
+----+---------------+-----+--------+
1 row in set (0.00 sec)
mysql> drop table myclass; -删除数据表
Query OK, 0 rows affected (0.03 sec)
mysql> drop database test_db; --删除数据库
Query OK, 0 rows affected (0.02 sec)