SQL内功心法之乾坤大挪移
发表于：2025-01-31 作者：千家信息网编辑
千家信息网最后更新 2025年01月31日，SQL： 指结构化查询语言，全称是 Structured Query Language。SQL语言包括三种主要程序设计语言类别的语句：数据定义语言(DDL)，数据操作语言(DML)及数据控制语言(DC
千家信息网最后更新 2025年01月31日SQL内功心法之乾坤大挪移
SQL： 指结构化查询语言，全称是 Structured Query Language。SQL语言包括三种主要程序设计语言类别的语句：数据定义语言(DDL)，数据操作语言(DML)及数据控制语言(DCL)。DCL：数据库控制语言，Data Control Language， 用来设置或更改数据库用户或角色权限的语句，【grant、remove,deny】DML：数据操纵语言，Data Manipulation Language ，命令使用户能够操作已有数据库中的数据的计算机语言 【Insert、delete、update】，处理表数据DDL：数据库模式定义语言，Data Definition Language ，是用于描述数据库中要存储的现实世界实体的语言【create，add,alter,drop】处理表结构DQL：数据查询语言，Data Query Language SELECT ，【select】
----------------------------------表结构------------------------------------------------------学生表 Student（编号student_code、姓名student_name、年龄student_age、性别student_sex）--课程表 Course（课程编号course_code、课程名称course_name、教师编号teacher_code）--成绩表 Score（学生编号student_code、课程编号course_code、成绩score）--教师表 Teacher（教师编号teacher_code、姓名teacher_name）
创建表：
CREATE TABLE Student (`student_code` varchar(255) NOT NULL COMMENT '学号' ,`student_name` varchar(255) NULL COMMENT '学生姓名' ,`student_sex` char(1) NULL COMMENT '性别' ,`student_age` varchar(255) NULL COMMENT '年龄' ,`create_by` varchar(255) NULL COMMENT '创建人' ,`create_date` datetime NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '创建日期' ,`update_by` varchar(255) NULL COMMENT '更新人' ,`updtae_date` datetime NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间' ,PRIMARY KEY (`student_code`));
CREATE TABLE Course (`course_code` varchar(255) NOT NULL COMMENT '课程号' ,`course_name` varchar(255) NULL COMMENT '课程姓名' ,`teacher_code` varchar(255) NULL COMMENT '教师编码' ,`create_by` varchar(255) NULL COMMENT '创建人' ,`create_date` datetime NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '创建日期' ,`update_by` varchar(255) NULL COMMENT '更新人' ,`updtae_date` datetime NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间' ,PRIMARY KEY (`course_code`));
CREATE TABLE Score (`student_code` varchar(255) NOT NULL COMMENT '学号' ,`course_code` varchar(255) NULL COMMENT '课程编码' ,`score` int(100) NULL COMMENT '成绩' );
CREATE TABLE Teacher (`teacher_code` varchar(255) NOT NULL COMMENT '教师编号' ,`teacher_name` varchar(255) NULL COMMENT '教师姓名' ,`create_by` varchar(255) NULL COMMENT '创建人' ,`create_date` datetime NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '创建日期' ,`update_by` varchar(255) NULL COMMENT '更新人' ,`updtae_date` datetime NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间' ,PRIMARY KEY (`teacher_code`));
插入数据：
---插入数据--INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709001', 'A001', '男', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709002', 'A002', '女', '22', 'system', '2017-01-03 15:08:38', 'system', '2017-01-03 15:08:38');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709003', 'A003', '女', '22', 'system', '2017-01-03 15:08:38', 'system', '2017-01-03 15:08:38');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709004', 'A004', '男', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709005', 'A005', '男', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709006', 'A006', '女', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709007', 'A007', '男', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709008', 'A008', '女', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709009', 'A009', '男', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709010', 'A010', '女', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709011', 'A011', '男', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');INSERT INTO `student` (`student_code`, `student_name`, `student_sex`, `student_age`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('201709012', 'A012', '男', '22', 'system', '2017-01-03 15:08:23', 'system', '2017-01-03 15:08:23');---插入数据--INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('Chinese', '语文', 'T001', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('Math', '数学', 'T002', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('English', '英语', 'T003', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('Physics', '物理', 'T004', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('Political', '政治', 'T005', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('Organism', '生物', 'T006', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('Geography', '地理', 'T007', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('History', '历史', 'T008', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');INSERT INTO `course` (`course_code`, `course_name`, `teacher_code`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('Chemistry', '化学', 'T009', 'system', '2017-01-03 15:19:18', 'system', '2017-01-03 15:19:32');---插入数据--INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709001', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709002', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709003', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709004', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709005', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709006', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709007', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709008', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709009', 'Political', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'Chemistry', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'Chinese', '90');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'English', '97');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'Geography', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'History', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'Math', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'Organism', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'Physics', '99');INSERT INTO `score` (`student_code`, `course_code`, `score`) VALUES ('201709010', 'Political', '99');---插入数据--INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T001', '王羲之', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T002', '赵匡胤', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T003', '赵明', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T004', '燕十三郎', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T005', '龙吟', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T006', '方言', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T007', '彭松', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T008', '唐宋', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');INSERT INTO `teacher` (`teacher_code`, `teacher_name`, `create_by`, `create_date`, `update_by`, `updtae_date`) VALUES ('T009', '张三丰', 'system', '2017-01-03 15:42:06', 'system', '2017-01-03 15:42:16');场景测试：
-- 1.查询"A"课程比"B"课程成绩高的所有学生的学号 SELECT student.student_code AS "StudentCode", student.student_name AS "StudentName"FROM Student studentWHERE ( SELECT score1.score FROM Score score1 WHERE score1.student_code = student.student_code AND score1.course_code = 'Chemistry' -- A课程 ) > ( SELECT score2.score FROM Score score2 WHERE score2.student_code = student.student_code AND score2.course_code = 'Chinese' -- B课程 );--2.查询平均成绩大于90分的同学的学号和平均成绩 SELECT score.student_code AS "StudentCode", AVG(score.score) AS " AVGScore"FROM Score scoreGROUP BY score.scoreHAVING AVG(score.score) > 90--3.查询所有同学的学号、姓名、选课数、总成绩； SELECT student.student_code AS "StudentCode",--学号 student.student_name AS "StudentName",--姓名 COUNT(score.course_code) AS "SelectCourse",--选课数 SUM(score.score) AS "SumScore"--总成绩FROM Student studentLEFT JOIN Score score ON score.student_code = student.student_codeGROUP BY student.student_code, student.student_name;--4、查询姓"张"的老师的个数； SELECT Count(*)FROM Teacher teacherWHERE teacher.teacher_name LIKE '张%';--5.查询没有学过"张三丰"老师课的同学的学号、姓名； SELECT student.student_code AS "StudentCode", student.student_name AS "StudentName"FROM Student studentWHERE student.student_code NOT IN ( SELECT DISTINCT (score.student_code) FROM Score score, Course course, Teacher teacher WHERE score.course_code = course.course_code AND teacher.teacher_code = course.course_code AND teacher.teacher_name = '张三丰' );
数据
语言
课程
姓名
学号
查询
成绩
更新
教师
数据库
学生
创建人
同学
日期
时间
结构
三丰
年龄
性别
总成
数据库的安全要保护哪些东西
数据库安全各自的含义是什么
生产安全数据库录入
数据库的安全性及管理
数据库安全策略包含哪些
海淀数据库安全审计系统
建立农村房屋安全信息数据库
易用的数据库客户端支持安全管理
连接数据库失败ssl安全错误
数据库的锁怎样保障安全
nfs依赖服务器
数据库分为用户数据库
李沧区管理系统软件开发哪家好
数据库加密与安全配置
微信数据库修复失败登录不了
小学国家网络安全宣传周主题
发票数据库制作
管理服务器工作
软件开发的注释
浙江省网络安全和信息化规定
警察网络安全工作
小程序腾讯云服务器接口调试
大学里是不是都有自己的数据库
用户行为数据库设计
青岛铭鼎网络技术有限公司
网络安全宣传周主要活动内容
外包软件开发公司
阿勒泰软件开发行业标准
象山应用软件开发教程
数据库1184拒绝连接
高品质的服务器监控工具
服务器文件操作管理软件
四级计算机数据库多少道题
南阳市公安局网络技术侦查
18款罗密欧网络安全模块位置
桂林移动七星数据库位置
万方具有哪个特色数据库
网络安全宣周传海报
中国科技与互联网发展前景
手抄网络安全我先行
