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OSI参考模型 1.OSI参考模型优点OSI模型是层次型的，具有所有分层模型的所有优点和好处，所有分层模型的主要目的是为了让不同厂商的网络能够互操作。2.使用OSI分层模型主要有以下几点：将网络通信过程划分成更小、更简单的组件。这有助于组件的开发、设计和故障排除；通过标准化网络组件，能够让多家厂商协作开发；定义了模型每层执行的功能；可以让不同类型的网络硬件和软件彼此通信；避免对其中一层的修改影响其它层，从而避免妨碍开发工作。3.OSI参考模型OSI规范最大的作用之一是帮助不同的主机之间进行数据传输，OSI模型包含7层，它们分为两组：上3层指定了终端的应用程序如何彼此通信以及如何与用户交流。下4层指定了如何进行端到端的数据传输。名称说明应用层提供用户界面表示层表示数据，进行加密等处理会话层将不同应用程序的数据分离传输层提供可靠或不可靠的传输，在重传前执行纠错网络层提供逻辑地址，路由器使用它们来选择路径数据链路层将分组拆分成字节，并将字节组合成帧，使用MAC地址提供介质访问，执行纠错检测，但不纠错物理层在设备之间传输比特，指定电平、电缆速度和电缆针脚
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test_db 下载数据库&样本库MySQL：https://downloads.mysql.com/archives/get/p/25/file/mysql-installer-community-8.0.15.0.msi 样本库：https://github.com/datacharmer/test_dbwget https://github.com/datacharmer/test_db/releases/download/v1.0.7/test_db-1.0.7.tar.gz1.数据库创建MySQL [employees]> SHOW CREATE DATABASE employees\G *************************** 1. row *************************** Database: employees Create Database: CREATE DATABASE `employees` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ 1 row in set (0.00 sec)2.视图 current_dept_empMySQL [employees]> SHOW TABLES; +----------------------+ | Tables_in_employees | +----------------------+ | current_dept_emp | | departments | | dept_emp | | dept_emp_latest_date | | dept_manager | | employees | | salaries | | titles | +----------------------+MySQL [employees]> DESC current_dept_emp; +-----------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+---------+------+-----+---------+-------+ | emp_no | int(11) | NO | | NULL | | | dept_no | char(4) | NO | | NULL | | | from_date | date | YES | | NULL | | | to_date | date | YES | | NULL | | +-----------+---------+------+-----+---------+-------+ 4 rows in set (0.01 sec)MySQL [employees]> SHOW CREATE VIEW current_dept_emp\G *************************** 1. row *************************** View: current_dept_emp Create View: CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `current_dept_emp` AS select `l`.`emp_no` AS `emp_no`,`d`.`dept_no` AS `dept_no`,`l`.`from_date` AS `from_date`,`l`.`to_date` AS `to_date` from (`dept_emp` `d` join `dept_emp_latest_date` `l` on(((`d`.`emp_no` = `l`.`emp_no`) and (`d`.`from_date` = `l`.`from_date`) and (`l`.`to_date` = `d`.`to_date`)))) character_set_client: utf8 collation_connection: utf8_general_ci3.表: departmentsMySQL [employees]> SHOW CREATE TABLE departments\G *************************** 1. row *************************** Table: departments Create Table: CREATE TABLE `departments` ( `dept_no` char(4) NOT NULL, `dept_name` varchar(40) NOT NULL, PRIMARY KEY (`dept_no`), UNIQUE KEY `dept_name` (`dept_name`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4MySQL [employees]> DESC departments; +-----------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+-------+ | dept_no | char(4) | NO | PRI | NULL | | | dept_name | varchar(40) | NO | UNI | NULL | | +-----------+-------------+------+-----+---------+-------+4.表：dept_empMySQL [employees]> SHOW CREATE TABLE dept_emp\G *************************** 1. row *************************** Table: dept_emp Create Table: CREATE TABLE `dept_emp` ( `emp_no` int(11) NOT NULL, `dept_no` char(4) NOT NULL, `from_date` date NOT NULL, `to_date` date NOT NULL, PRIMARY KEY (`emp_no`,`dept_no`), KEY `dept_no` (`dept_no`), CONSTRAINT `dept_emp_ibfk_1` FOREIGN KEY (`emp_no`) REFERENCES `employees` (`emp_no`) ON DELETE CASCADE, CONSTRAINT `dept_emp_ibfk_2` FOREIGN KEY (`dept_no`) REFERENCES `departments` (`dept_no`) ON DELETE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4MySQL [employees]> DESC dept_emp; +-----------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+---------+------+-----+---------+-------+ | emp_no | int(11) | NO | PRI | NULL | | | dept_no | char(4) | NO | PRI | NULL | | | from_date | date | NO | | NULL | | | to_date | date | NO | | NULL | | +-----------+---------+------+-----+---------+-------+5.表：dept_managerMySQL [employees]> SHOW CREATE TABLE dept_manager\G *************************** 1. row *************************** Table: dept_manager Create Table: CREATE TABLE `dept_manager` ( `emp_no` int(11) NOT NULL, `dept_no` char(4) NOT NULL, `from_date` date NOT NULL, `to_date` date NOT NULL, PRIMARY KEY (`emp_no`,`dept_no`), KEY `dept_no` (`dept_no`), CONSTRAINT `dept_manager_ibfk_1` FOREIGN KEY (`emp_no`) REFERENCES `employees` (`emp_no`) ON DELETE CASCADE, CONSTRAINT `dept_manager_ibfk_2` FOREIGN KEY (`dept_no`) REFERENCES `departments` (`dept_no`) ON DELETE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4MySQL [employees]> DESC dept_manager; +-----------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+---------+------+-----+---------+-------+ | emp_no | int(11) | NO | PRI | NULL | | | dept_no | char(4) | NO | PRI | NULL | | | from_date | date | NO | | NULL | | | to_date | date | NO | | NULL | | +-----------+---------+------+-----+---------+-------+6.表：employeesMySQL [employees]> SHOW CREATE TABLE employees\G *************************** 1. row *************************** Table: employees Create Table: CREATE TABLE `employees` ( `emp_no` int(11) NOT NULL, `birth_date` date NOT NULL, `first_name` varchar(14) NOT NULL, `last_name` varchar(16) NOT NULL, `gender` enum('M','F') NOT NULL, `hire_date` date NOT NULL, PRIMARY KEY (`emp_no`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4MySQL [employees]> DESC employees; +------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +------------+---------------+------+-----+---------+-------+ | emp_no | int(11) | NO | PRI | NULL | | | birth_date | date | NO | | NULL | | | first_name | varchar(14) | NO | | NULL | | | last_name | varchar(16) | NO | | NULL | | | gender | enum('M','F') | NO | | NULL | | | hire_date | date | NO | | NULL | | +------------+---------------+------+-----+---------+-------+7.表: salariesMySQL [employees]> SHOW CREATE TABLE salaries\G *************************** 1. row *************************** Table: salaries Create Table: CREATE TABLE `salaries` ( `emp_no` int(11) NOT NULL, `salary` int(11) NOT NULL, `from_date` date NOT NULL, `to_date` date NOT NULL, PRIMARY KEY (`emp_no`,`from_date`), CONSTRAINT `salaries_ibfk_1` FOREIGN KEY (`emp_no`) REFERENCES `employees` (`emp_no`) ON DELETE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4MySQL [employees]> DESC salaries; +-----------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+---------+------+-----+---------+-------+ | emp_no | int(11) | NO | PRI | NULL | | | salary | int(11) | NO | | NULL | | | from_date | date | NO | PRI | NULL | | | to_date | date | NO | | NULL | | +-----------+---------+------+-----+---------+-------+8.表: titlesMySQL [employees]> SHOW CREATE TABLE titles\G *************************** 1. row *************************** Table: titles Create Table: CREATE TABLE `titles` ( `emp_no` int(11) NOT NULL, `title` varchar(50) NOT NULL, `from_date` date NOT NULL, `to_date` date DEFAULT NULL, PRIMARY KEY (`emp_no`,`title`,`from_date`), CONSTRAINT `titles_ibfk_1` FOREIGN KEY (`emp_no`) REFERENCES `employees` (`emp_no`) ON DELETE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4MySQL [employees]> DESC titles; +-----------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+-------+ | emp_no | int(11) | NO | PRI | NULL | | | title | varchar(50) | NO | PRI | NULL | | | from_date | date | NO | PRI | NULL | | | to_date | date | YES | | NULL | | +-----------+-------------+------+-----+---------+-------+
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MySQL - SHOW语句 SHOW 语句MySQL [(none)]> HELP SHOW;一. SHOW {BINARY | MASTER} LOGS 列出二进制列表MySQL [(none)]> SHOW BINARY LOGS\G *************************** 1. row *************************** Log_name: mysql-bin.000015 File_size: 4714627 2 rows in set (0.00 sec) MySQL [(none)]> SHOW MASTER LOGS\G *************************** 1. row *************************** Log_name: mysql-bin.000015 File_size: 4714627 2 rows in set (0.00 sec)二. SHOW BINLOG EVENTS [IN 'log_name'] [FROM pos] [LIMIT [offset,] row_count] 列出二进制日志事件IN 'log_name' 指定要查询的binlog文件名(不指定就是第一个binlog文件)FROM pos 指定从哪个pos起始点开始查起(不指定就是从整个文件首个pos点开始算)LIMIT [offset,] 偏移量(不指定就是0)row_count 查询总条数(不指定就是所有行)MySQL [(none)]> SHOW BINLOG EVENTS IN 'mysql-bin.000015' LIMIT 3,2\G *************************** 1. row *************************** Log_name: mysql-bin.000015 Pos: 219 Event_type: Query Server_id: 1 End_log_pos: 300 Info: BEGIN *************************** 2. row *************************** Log_name: mysql-bin.000015 Pos: 300 Event_type: Query Server_id: 1 End_log_pos: 526rows in set (0.01 sec) SHOW CHARACTER SET [like_or_where] SHOW COLLATION [like_or_where] SHOW [FULL] COLUMNS FROM tbl_name [FROM db_name] [like_or_where] SHOW CREATE DATABASE db_name SHOW CREATE EVENT event_name SHOW CREATE FUNCTION func_name SHOW CREATE PROCEDURE proc_name SHOW CREATE TABLE tbl_name SHOW CREATE TRIGGER trigger_name SHOW CREATE VIEW view_name SHOW DATABASES [like_or_where] SHOW ENGINE engine_name {STATUS | MUTEX} SHOW [STORAGE] ENGINES SHOW ERRORS [LIMIT [offset,] row_count] SHOW EVENTS SHOW FUNCTION CODE func_name SHOW FUNCTION STATUS [like_or_where] SHOW GRANTS FOR user SHOW INDEX FROM tbl_name [FROM db_name] SHOW MASTER STATUS SHOW OPEN TABLES [FROM db_name] [like_or_where] SHOW PLUGINS SHOW PROCEDURE CODE proc_name SHOW PROCEDURE STATUS [like_or_where] SHOW PRIVILEGES SHOW [FULL] PROCESSLIST SHOW PROFILE [types] [FOR QUERY n] [OFFSET n] [LIMIT n] SHOW PROFILES SHOW RELAYLOG EVENTS [IN 'log_name'] [FROM pos] [LIMIT [offset,] row_count] SHOW SLAVE HOSTS SHOW SLAVE STATUS [FOR CHANNEL channel] SHOW [GLOBAL | SESSION] STATUS [like_or_where] SHOW TABLE STATUS [FROM db_name] [like_or_where] SHOW [FULL] TABLES [FROM db_name] [like_or_where] SHOW TRIGGERS [FROM db_name] [like_or_where] SHOW [GLOBAL | SESSION] VARIABLES [like_or_where] SHOW WARNINGS [LIMIT [offset,] row_count] like_or_where: { LIKE 'pattern' | WHERE expr } If the syntax for a given SHOW statement includes a LIKE 'pattern' part, 'pattern' is a string that can contain the SQL % and _ wildcard characters. The pattern is useful for restricting statement output to matching values. Several SHOW statements also accept a WHERE clause that provides more flexibility in specifying which rows to display. See https://dev.mysql.com/doc/refman/5.7/en/extended-show.html. URL: https://dev.mysql.com/doc/refman/5.7/en/show.html
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JDK环境变量设置 WindowsJAVA_HOME=C:\Program Files\Java\jdk1.8.0_191 CLASSPATH=.;%JAVA_HOME%\lib;%JAVA_HOME%\lib\tools.jar PATH=%JAVA_HOME%\bin;%JAVA_HOME%\jre\bin;Linuxvi /etc/profile.d/jdk.sh export JAVA_HOME=/usr/local/java/jdk1.8.0_191 export PATH=$JAVA_HOME/bin:$PATH export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar使jdk.sh生效source /etc/profile.d/jdk.sh
