简单设置环境变量，以及密码
1.把mysql命令加入环境变量
[root@master01 ~]# vim /etc/profile.d/mysql.sh

!/bin/bash

export MYSQL=/application/mysql
export PATH=$PATH:$MYSQL/bin
[root@master01 ~]# source /etc/profile.d/mysql.sh

2.输入命令进入数据库
[root@master01 ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.6.40 Source distribution

Copyright (c) 2000, 2018, 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> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)

mysql> drop database test;
Query OK, 0 rows affected (0.01 sec)

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
+--------------------+
3 rows in set (0.00 sec)

mysql>

3.由于数据库初始没有密码,我们需要在命令行设置密码
mysqladmin -uroot -p password

交互式隐藏输入密码,比较安全
自己自定义设置,安全好记的密码

4.登录测试密码
[root@master01 ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.6.40 Source distribution

Copyright (c) 2000, 2018, 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> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
+--------------------+
3 rows in set (0.00 sec)

mysql>