1、以Windows系统为例，通过cmd命令行登录mysql数据库的命令为：
mysql -p(password) -u(username) -h(service IP)
登录提示：
[Warning] Using a password on the command line interface can be insecure.
[警告]直接在命令行使用明码密码是不安全的
推荐使用命令mysql -p -u(username) -h(service IP)；先不直接输入密码，提示Enter password，再输入密码，可以借居然以上问题。
成功登录mysql之后，提示如下：
Welcome to the MySQL monitor. Commands end with ; or \g.[提示：mysql命令以;或者\g为结束符]
Your MySQL connection id is 22
Server version: 5.7.11-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, 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.
[提示：键入help或者\h可以获取帮助信息；clear或者\c可以清除当前键入的命令]
2、键入help输出帮助信息如下：
Note that all text commands must be first on line and end with \';\'
? (\?) Synonym for `help\'.
clear (\c) Clear the current input statement.
connect (\r) Reconnect to the server. Optional arguments are db and host.
delimiter (\d) Set statement delimiter.
ego (\G) Send command to mysql server, display result vertically.
exit (\q) Exit mysql. Same as quit.
go (\g) Send command to mysql server.
help (\h) Display this help.
notee (\t) Don\'t write into outfile.
print (\p) Print current command.
prompt (\R) Change your mysql prompt.
quit (\q) Quit mysql.
rehash (\#) Rebuild completion hash.
source (\.) Execute an SQL script file. Takes a file name as an argument.
status (\s) Get status information from the server.
tee (\T) Set outfile [to_outfile]. Append everything into given outfile.
use (\u) Use another database. Takes database name as argument.
charset (\C) Switch to another charset. Might be needed for processing binlog
with multi-byte charsets.
warnings (\W) Show warnings after every statement.
nowarning (\w) Don\'t show warnings after every statement.
