参数说明：-u 表示指定用户，-u与root用户名之间的空格可省略-p 表示会提示输入密码，-p与密码之间不能存在空格-S 指定套接字位置-h 指定远端的mysql主机-P 大写，指定musql服务对应的端口-e 指定执行的sql语句-------------------------------
1、本地连接
2、远程连接（多用于脚本）将密码直接写在文件，方便登陆（不安全）
[root@node2 ~]# more /usr/bin/my
mysql -uroot -p'MoRui!@#'
[root@node2 ~]# my
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 3
Server version: 5.7.25 MySQL Community Server (GPL)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>1、交互式输入密码：
[root@node2 ~]# mysql -u root -p
Enter password: 2、指定密码：
[root@node2 ~]# mysql -u root -p1234563、在本地连接mysql时，可以指定哪个套接字文件连接到数据库，通过-S指定套接字位置(比较少用)
[root@node2 ~]# mysql -uroot -p123456 -S  /var/lib/mysql/mysql.sock4、连接到远程mysql主机
-h 指定远端的mysql主机
-P 大写，指定musql服务对应的端口
连接的前提是已经授权当前客户端的ip地址能够连接到数据库
mysql -u root -p123456 -h 192.168.100.50 -P 33065、连接数据库的同时执行对应的命令（常用于shell脚本中）
-e 指定执行的sql语句
mysql -u root -p123456 -e 'use mysql;select user,host,password form user;'root@node1:~#  mysql -uroot -p'Study2019!@#' -h 119.27.187.118 -P 3306  -e 'use mysql;select user,host,authentication_string from user;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+-----------+-----------+-------------------------------------------+
| user      | host      | authentication_string                     |
+-----------+-----------+-------------------------------------------+
| root      | localhost | *6F77D0F641432E14D4AAE5CCAF1E4341A241EAAC |
| mysql.sys | localhost | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE |
+-----------+-----------+-------------------------------------------+mysql -u root -p123456 -e 'create database if not exists testdb; show databases;'
查看数据库版本:
mysql> select version();
+-----------+
| version() |
+-----------+
| 5.7.25    |
+-----------+
1 row in set (0.00 sec)
查看当前用户:
mysql> select user();
+----------------+
| user()         |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
查看当前时间:
mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2019-03-03 21:36:45 |
+---------------------+
1 row in set (0.00 sec)