3.1数据库连接管理
登录数据库系统
在命令行中登录mysql数据库管理系统，其中“-h”参数指连接的主机名，因为此处是连接本机，所以后面的内容为localhost；“-u”参数表示用户名，此处的用户名为root：“-p”参数指用户密码。按下回车键显示输入密码提示mysql -h localhost -u root -p
3.2数据库的启动流程图介绍
3.3 mysql命令，接口自带功能（常用举例）
\h或help或？
**mysql> \h #？号的效果相同的
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https://shop.mysql.com/
List of all MySQL commands:
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.
edit (\e) Edit command with $EDITOR.
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.
nopager (\n) Disable pager, print to stdout.
notee (\t) Don't write into outfile.
pager (\P) Set PAGER [to_pager]. Print the query results via PAGER.
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.
system (\!) Execute a system shell command.
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.
For server side help, type 'help contents'**3.4\Gmysql中在sql语句后面加\G表示将查询结果按列打印，默认情况下，mysql的查询结果是横向输出的，第一行是列头，后面是记录集，
3.5\c或者CTRL+c 这里表示的是取消的意思mysql> asdfasdlkjlds \c
3.6mysql命令，source命令使用
在mysql中处理文件
如果这些文件包含sql语句，则称为“脚本文件”，“批处理文件”
使用SOURCE命令mysql> source /root/world.sql
3.7 mysql数据库的关闭
方法一：mysqladmin -uroot -p123456 shutdown
方法二：service mysqld stop
方法三：/etc/init.d/mysqld stop
第四种方法是利用系统进程管理命令关闭mysql
kill pid #这里的pid为数据库服务对应的进程号
killall mysqld #这里的mysqld是数据库对应的进程名字
pkill mysqld #这里的mysqld是数据库服务对应的进程名字
3.8my.cnf配置文件说明
影响到服务器进程的启动
影响到客户端程序
mysql程序主配置文件
3.9配置文件读取过程/etc/my.cnf --> /etc/mysql/my.cnf --> $MYSQL_HOME/my.cnf --> defaults-extra-file=/tmp/clsn.txt --> ~/.my.cnf
