mysql80-DBA数据库学习1

掌握能力

核心技能

核心技能

mysql部署

官网地址www.mysql.com  或者www.oracle.com

https://dev.mysql.com/downloads/repo/yum/

Install the RPM you downloaded for your system, for example:

yum install mysql80-community-release-{platform}-{version-number}.noarch.rpm

yum repolist

(3/3): mysql80-community/x86_64/primary_db                                               | 278 kB  00:00:01     
源标识                                                   源名称                                            状态
!c7-media                                                CentOS-7 - Media                                  4,070
mysql-connectors-community/x86_64                        MySQL Connectors Community                          242
mysql-tools-community/x86_64                             MySQL Tools Community                               104
mysql80-community/x86_64                                 MySQL 8.0 Community Server                          465
repolist: 4,881

新安装了三个关于mysql的仓库

[root@localhost ~]# yum repolist all | grep mysq

[root@localhost ~]# yum repolist all | grep mysq
file:///media/repodata/repomd.xml: [Errno 14] curl#37 - "Couldn't open file /media/repodata/repomd.xml"
正在尝试其它镜像。
mysql-cluster-7.5-community/x86_64                  MySQL Cluster 7. 禁用
mysql-cluster-7.5-community-source                  MySQL Cluster 7. 禁用
mysql-cluster-7.6-community/x86_64                  MySQL Cluster 7. 禁用
mysql-cluster-7.6-community-source                  MySQL Cluster 7. 禁用
mysql-cluster-8.0-community/x86_64                  MySQL Cluster 8. 禁用
mysql-cluster-8.0-community-debuginfo/x86_64        MySQL Cluster 8. 禁用
mysql-cluster-8.0-community-source                  MySQL Cluster 8. 禁用
mysql-cluster-innovation-community/x86_64           MySQL Cluster In 禁用
mysql-cluster-innovation-community-debuginfo/x86_64 MySQL Cluster In 禁用
mysql-cluster-innovation-community-source           MySQL Cluster In 禁用
mysql-connectors-community/x86_64                   MySQL Connectors 启用:   242
mysql-connectors-community-debuginfo/x86_64         MySQL Connectors 禁用
mysql-connectors-community-source                   MySQL Connectors 禁用
mysql-innovation-community/x86_64                   MySQL Innovation 禁用
mysql-innovation-community-debuginfo/x86_64         MySQL Innovation 禁用
mysql-innovation-community-source                   MySQL Innovation 禁用
mysql-tools-community/x86_64                        MySQL Tools Comm 启用:   104
mysql-tools-community-debuginfo/x86_64              MySQL Tools Comm 禁用
mysql-tools-community-source                        MySQL Tools Comm 禁用
mysql-tools-innovation-community/x86_64             MySQL Tools Inno 禁用
mysql-tools-innovation-community-debuginfo/x86_64   MySQL Tools Inno 禁用
mysql-tools-innovation-community-source             MySQL Tools Inno 禁用
mysql-tools-preview/x86_64                          MySQL Tools Prev 禁用
mysql-tools-preview-source                          MySQL Tools Prev 禁用
mysql57-community/x86_64                            MySQL 5.7 Commun 禁用
mysql57-community-source                            MySQL 5.7 Commun 禁用
mysql80-community/x86_64                            MySQL 8.0 Commun 启用:   465
mysql80-community-debuginfo/x86_64                  MySQL 8.0 Commun 禁用
mysql80-community-source                            MySQL 8.0 Commun 禁用

Install MySQL by the following command (for dnf-enabled systems, replace yum in the command ):

$> sudo yum install mysql-community-server

Start the MySQL server with the following command:

$> systemctl start mysqld

You can check the status of the MySQL server with the following command:

$> systemctl status mysqld
$>systemctl enable mysqld

mysql -uroot -p 登录异常,

A superuser account 'root'@'localhost is created. A password for the superuser is set and stored in the error log file. To reveal it, use the following command:

$> sudo grep 'temporary password' /var/log/mysqld.log
[root@localhost ~]# grep 'temporary password' /var/log/mysqld.log
2024-03-20T09:36:13.003622Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: !R,V#Fj8qi*P
[root@localhost ~]# mysql -uroot -p                              
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
[root@localhost ~]# mysql -uroot -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@localhost ~]# grep 'temporary password' /var/log/mysqld.log
2024-03-20T09:36:13.003622Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: !R,V#Fj8qi*P

!R,V#Fj8qi*P就是root密码

mysql -uroot -p

输入!R,V#Fj8qi*P

Change the root password as soon as possible by logging in with the generated, temporary password and set a custom password for the superuser account:

$> mysql -uroot -p
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass4!';ALTER USER 'root'@'localhost' IDENTIFIED BY 'Root@098';

国内镜像安装

mirrors.ustc.edu.cn这个是中科大的镜像系统

下载如下rpm

mysql-community-client-8.0.36-1.el7.x86_64
mysql-community-common-8.0.36-1.el7.x86_64
mysql-community-libs-8.0.36-1.el7.x86_64
mysql-community-icu-data-files-8.0.36-1.el7.x86_64
mysql-community-libs-compat-8.0.36-1.el7.x86_64
mysql-community-client-plugins-8.0.36-1.el7.x86_64
mysql-community-server-8.0.36-1.el7.x86_64

如果用centos7去装MySQL5.7 还需要额外的安装3个包

libaio.x86_64  perl.x86_64 net-tools.x86_64 

到当前下载文件的目录下

yum install -y *.rpm就会安装下载的包了

systemctl start mysqld 启动mysql

systemctl enable mysqld 开机启动mysql

netstat -anpt 查看端口号

systemctl status mysqld 查看服务启动状态

mysql -uroot -p提示登录失败

解决方法

grep  “password” /var/log/mysqld.log

[root@localhost ~]# grep "password" /var/log/mysqld.log 
2024-03-20T09:36:13.003622Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: !R,V#Fj8qi*P
[root@localhost ~]# 

在root@localhost:后的内容为mysql的root密码

mysql》show databases;报错 提示需要改密码

#mysqladmin -uroot -p'!R,V#Fj8qi*P'  password 'Qianfeng@123'

有个小警告,

或者mysql>下使用

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass4!';

虚拟机环境这时可以做一个快照 名字为mysql安装后,后期操作混乱后可以恢复到次快照

1.rpm安装

2.源码安装

3自建mysql-yum仓库

--------------------------------------------------------------------------------------------------------------------------------

mysql忘记root密码

首先,去配置文件/etc/my.cnf):

【mysqld】

添加skip-grant-tables

重启mysql   systemctl restart mysqld

mysql -uroot -p  此时无密码

use mysql;

配置root密码为空

update user set authentication_string='' where user='root';

quit 退出

使用# 注销配置文件my.cnf的 skip-grant-tables

重启mysql systemctl restart mysqld

mysql -uroot 回车  无密码

ALTER user 'root'@'localhost' IDENTIFIED BY 'Root@098';

Root@098为新密码

为了保障,最好还是多创建一个超级特权用户:

CREATE USER '账号'@'%' IDENTIFIED BY '密码';

GRANT ALL PRIVILEGES ON *.* TO '账号'@'%' WITH GRANT OPTION;

最后刷新权限 flush privileges;

---------------------------------------------------------------------------------------------------------------------------------

数据库操作

建库:

mysql> create database discuz;
Query OK, 1 row affected (0.01 sec)

查看数据库:

show databases;

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| discuz             |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.01 sec)
mysql> create database DISCUZ;
Query OK, 1 row affected (0.01 sec)mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| DISCUZ             |
| discuz             |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
6 rows in set (0.00 sec)mysql> 

注意:数据库的名字严格区分大小写

DISCUZ 和discuz是不同的数据库

mysql输入 “”回车“”不是执行和结束,结束需要用“;

数据库名字  不能用关键字、不能单独用数字和特殊字符、常用拼音和单词来定义。

使用某个数据库

USE +数据库名字

mysql> use discuz;
Database changed

mysql> select database();查看我在那个数据库中

mysql> select database();
+------------+
| database() |
+------------+
| discuz     |
+------------+
1 row in set (0.00 sec)mysql> 

删除数据库drop database +名字

mysql> drop database DISCUZ;
Query OK, 0 rows affected (0.01 sec)

数据库备份

确定目录

如果是源码安装,配置文件中的配置项 datadir=/usr/local/mysql/这个目录就是后期的数据库实体目录。

yum或者rpm安装的mysql的文件默认目录为/var/lib/mysql ,这个目录为数据库的实体文件目录,

[root@localhost ~]# cd /var/lib/mysql
[root@localhost mysql]# ls
auto.cnf       binlog.000004  ca-key.pem       discuz             ibdata1       mysql            performance_schema  server-key.pem
binlog.000001  binlog.000005  ca.pem           #ib_16384_0.dblwr  ibtmp1        mysql.ibd        private_key.pem     sys
binlog.000002  binlog.000006  client-cert.pem  #ib_16384_1.dblwr  #innodb_redo  mysql.sock       public_key.pem      undo_001
binlog.000003  binlog.index   client-key.pem   ib_buffer_pool     #innodb_temp  mysql.sock.lock  server-cert.pem     undo_002
[root@localhost mysql]# 

discuz目录就是我们创建的数据库。

创建表create tables 表名

create table t1 (id int);

mysql> create table t2 (id int);
Query OK, 0 rows affected (0.03 sec)mysql> 

表的描述说明 desc +表名

mysql> create table t2 (id int);
Query OK, 0 rows affected (0.03 sec)mysql> create table t3 (id int,name varchar(20));
Query OK, 0 rows affected (0.03 sec)mysql> desc t2;
+-------+------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------+------+-----+---------+-------+
| id    | int  | YES  |     | NULL    |       |
+-------+------+------+-----+---------+-------+
1 row in set (0.01 sec)mysql> desc t3;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id    | int         | YES  |     | NULL    |       |
| name  | varchar(20) | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)

默认值 default

key主键

null 可否为空

type 字段类型

extra 外键

表的数据插入及查询  select insert  

insert 字符需要用到双引号   例如"liuyang"

mysql> insert into t3 values (1,"liuyang");
Query OK, 1 row affected (0.02 sec)mysql> insert into t3 values (2,"wangyan");
Query OK, 1 row affected (0.01 sec)mysql> select * from t3;
+------+---------+
| id   | name    |
+------+---------+
|    1 | liuyang |
|    2 | wangyan |
+------+---------+
2 rows in set (0.00 sec)mysql> 

综合例子

mysql> create database school;
Query OK, 1 row affected (0.01 sec)mysql> use school;
Database changed
mysql> create table student1 (id int,-> name varchar(20),-> sex enum('m','f'),-> age int);
Query OK, 0 rows affected (0.09 sec)mysql> desc student1;
+-------+---------------+------+-----+---------+-------+
| Field | Type          | Null | Key | Default | Extra |
+-------+---------------+------+-----+---------+-------+
| id    | int           | YES  |     | NULL    |       |
| name  | varchar(20)   | YES  |     | NULL    |       |
| sex   | enum('m','f') | YES  |     | NULL    |       |
| age   | int           | YES  |     | NULL    |       |
+-------+---------------+------+-----+---------+-------+
4 rows in set (0.00 sec)mysql> insert into student1 values (1,'zhangsan','m',23);
Query OK, 1 row affected (0.01 sec)mysql> insert into student1 values (2,'lisi','f',22);
Query OK, 1 row affected (0.00 sec)mysql> insert into student1 values (3,'wangwu','v',22);
ERROR 1265 (01000): Data truncated for column 'sex' at row 1
mysql> insert into student1 values (3,'wangwu','m',22);
Query OK, 1 row affected (0.01 sec)mysql> select * from student1;
+------+----------+------+------+
| id   | name     | sex  | age  |
+------+----------+------+------+
|    1 | zhangsan | m    |   23 |
|    2 | lisi     | f    |   22 |
|    3 | wangwu   | m    |   22 |
+------+----------+------+------+
3 rows in set (0.00 sec)mysql> 

DQL查询

创造数据


mysql> create database haha;
Query OK, 1 row affected (0.01 sec)mysql> use haha;
Database changed
mysql> create table t3 (id int,name varchar(20),age int);
Query OK, 0 rows affected (0.03 sec)mysql> insert into t3 values values (1,'zhangsan',23);
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'values (1,'zhangsan',23)' at line 1
mysql> insert into t3 values (1,'zhangsan',23);
Query OK, 1 row affected (0.01 sec)mysql> insert into t3 values (2,'lisi',24);
Query OK, 1 row affected (0.00 sec)mysql> insert into t3 values (3,'wangwu',18);
Query OK, 1 row affected (0.00 sec)mysql> 

create

mysql> create database company;
Query OK, 1 row affected (0.01 sec)mysql> create table company.employee5(
id int primary key AUTO_INCREMENT not null,
name varchar(30) not null,
sex enum('male','female') default 'male' not null,
hire_date date not null,
post varchar(50) not null,
job_description varchar(100),
salary double(15,2) not null,
office int,
dep_id int);
mysql> desc company.employee5-> ;
+-----------------+-----------------------+------+-----+---------+----------------+
| Field           | Type                  | Null | Key | Default | Extra          |
+-----------------+-----------------------+------+-----+---------+----------------+
| id              | int                   | NO   | PRI | NULL    | auto_increment |
| name            | varchar(30)           | NO   |     | NULL    |                |
| sex             | enum('male','female') | NO   |     | male    |                |
| hire_date       | date                  | NO   |     | NULL    |                |
| job_description | varchar(100)          | YES  |     | NULL    |                |
| salary          | double(15,2)          | NO   |     | NULL    |                |
| office          | int                   | YES  |     | NULL    |                |
| dep_id          | int                   | YES  |     | NULL    |                |
+-----------------+-----------------------+------+-----+---------+----------------+
8 rows in set (0.00 sec)mysql> 

insert

insert into company.employee5(name,sex,hire_date,post,job_description,salary,office,dep_id) values
('jack','male','20180202','instructor','teach',5000,501,100),
('tom','male','20180203','instructor','teach',5500,501,100),
('robin','male','20180202','instructor','teach',8000,501,100),
('alice','female','20180202','instructor','teach',7200,501,100),
('tianyun','male','20180202','hr','hrcc',600,502,101),
('harry','male','20180202','hr',NULL,6000,502,101),
('emma','female','20180206','sale','salecc',20000,503,102),
('christine','female','20180205','sale','salecc',2200,503,102),
('zhuzhu','male','20180205','sale',NULL,2200,503,102),
('gougou','male','20180205','sale','',2200,503,102);

select

mysql> select * from company.employee5;
+----+-----------+--------+------------+------------+-----------------+----------+--------+--------+
| id | name      | sex    | hire_date  | post       | job_description | salary   | office | dep_id |
+----+-----------+--------+------------+------------+-----------------+----------+--------+--------+
|  1 | jack      | male   | 2018-02-02 | instructor | teach           |  5000.00 |    501 |    100 |
|  2 | tom       | male   | 2018-02-03 | instructor | teach           |  5500.00 |    501 |    100 |
|  3 | robin     | male   | 2018-02-02 | instructor | teach           |  8000.00 |    501 |    100 |
|  4 | alice     | female | 2018-02-02 | instructor | teach           |  7200.00 |    501 |    100 |
|  5 | tianyun   | male   | 2018-02-02 | hr         | hrcc            |   600.00 |    502 |    101 |
|  6 | harry     | male   | 2018-02-02 | hr         | NULL            |  6000.00 |    502 |    101 |
|  7 | emma      | female | 2018-02-06 | sale       | salecc          | 20000.00 |    503 |    102 |
|  8 | christine | female | 2018-02-05 | sale       | salecc          |  2200.00 |    503 |    102 |
|  9 | zhuzhu    | male   | 2018-02-05 | sale       | NULL            |  2200.00 |    503 |    102 |
| 10 | gougou    | male   | 2018-02-05 | sale       |                 |  2200.00 |    503 |    102 |
+----+-----------+--------+------------+------------+-----------------+----------+--------+--------+
10 rows in set (0.00 sec)

select 排序

order by 

例如  +asc升序 默认

select name,salary from company.employee5 order by salary asc; 按照salary升序排列。

mysql> select name,salary from company.employee5 order by salary asc;
+-----------+----------+
| name      | salary   |
+-----------+----------+
| tianyun   |   600.00 |
| christine |  2200.00 |
| zhuzhu    |  2200.00 |
| gougou    |  2200.00 |
| jack      |  5000.00 |
| tom       |  5500.00 |
| harry     |  6000.00 |
| alice     |  7200.00 |
| robin     |  8000.00 |
| emma      | 20000.00 |
+-----------+----------+
10 rows in set (0.00 sec)

desc 降序

mysql> select name,salary from company.employee5 order by salary desc;
+-----------+----------+
| name      | salary   |
+-----------+----------+
| emma      | 20000.00 |
| robin     |  8000.00 |
| alice     |  7200.00 |
| harry     |  6000.00 |
| tom       |  5500.00 |
| jack      |  5000.00 |
| christine |  2200.00 |
| zhuzhu    |  2200.00 |
| gougou    |  2200.00 |
| tianyun   |   600.00 |
+-----------+----------+
10 rows in set (0.00 sec)

limit 3 限制,只输出3行

mysql> select name,salary from company.employee5 order by salary desc limit 4;
+-------+----------+
| name  | salary   |
+-------+----------+
| emma  | 20000.00 |
| robin |  8000.00 |
| alice |  7200.00 |
| harry |  6000.00 |
+-------+----------+
4 rows in set (0.00 sec)

本文来自互联网用户投稿,该文观点仅代表作者本人,不代表本站立场。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如若转载,请注明出处:http://www.rhkb.cn/news/284784.html

如若内容造成侵权/违法违规/事实不符,请联系长河编程网进行投诉反馈email:809451989@qq.com,一经查实,立即删除!

相关文章

Qt 写一个邮件发送程序

最近在完成一个邮箱代替的告警功能&#xff0c;写了一个邮件发送的demo 以下为代码&#xff1a; #ifndef MAINWINDOW_H #define MAINWINDOW_H#include <QMainWindow> #include<QTcpSocket> namespace Ui { class MainWindow; }class MainWindow : public QMainWin…

【STL源码剖析】【2、空间配置器——allocator】

文章目录 1、什么是空间配置器&#xff1f;1.1设计一个简单的空间配置器&#xff0c;JJ::allocator 2、具备次配置力( sub-allocation)的 SGI 空间配置器2.1 什么是次配置力2.2 SGI标准的空间配置器&#xff0c;std::allocator2.2 SGI特殊的空间配置器&#xff0c;std::alloc2.…

Java代码基础算法练习-公式求和-2024.03.24

任务描述&#xff1a; 求公式Snaaaaaa…aa…aaa&#xff08;有n个a&#xff09;之值&#xff0c;其中a是一个数字&#xff0c;为2。 例如&#xff0c;n5 时222222222222222&#xff0c;n 由键盘输入(n<5)。 任务要求&#xff1a; package march0317_0331;import java.util.…

【大模型】在VS Code(Visual Studio Code)上安装中文汉化版插件

文章目录 一、下载安装二、配置显示语言&#xff08;一&#xff09;调出即将输入命令的搜索模式&#xff08;二&#xff09;在大于号后面输入&#xff1a;Configure Display Language&#xff08;三&#xff09;重启 三、总结 【运行系统】win 11 【本文解决的问题】 1、英文不…

代码随想录算法训练营第三十一天|455.分发饼干,376.摆动序列,53. 最大子序和

455.分发饼干 题目 假设你是一位很棒的家长&#xff0c;想要给你的孩子们一些小饼干。但是&#xff0c;每个孩子最多只能给一块饼干。 对每个孩子 i&#xff0c;都有一个胃口值 g[i]&#xff0c;这是能让孩子们满足胃口的饼干的最小尺寸&#xff1b;并且每块饼干 j&#xff…

wy的leetcode刷题记录_Day93

wy的leetcode刷题记录_Day93 声明 本文章的所有题目信息都来源于leetcode 如有侵权请联系我删掉! 时间&#xff1a;2024-3-23 前言 目录 wy的leetcode刷题记录_Day93声明前言2549. 统计桌面上的不同数字题目介绍思路代码收获 827. 最大人工岛题目介绍思路代码收获 200. 岛屿…

【Godot4.2】像素直线画法及点求取函数

概述 基于CanvasItem提供的绘图函数进行线段绘制只需要直接调用draw_line函数就可以了。 但是对于可以保存和赋值节点直接使用的纹理图片&#xff0c;却需要依靠Image类。而Image类没有直接提供基于像素的绘图函数。只能依靠set_pixel或set_pixelv进行逐个像素的填色。 所以…

数字乡村发展策略:科技引领农村实现跨越式发展

随着信息技术的迅猛发展和数字经济的崛起&#xff0c;数字乡村发展策略已经成为引领农村实现跨越式发展的重要手段。科技的力量正在深刻改变着传统农业的生产方式、农村的社会结构以及农民的生活方式&#xff0c;为农村经济发展注入了新的活力和动力。本文将从数字乡村的内涵、…

java每日一题——买啤酒(递归经典问题)

前言&#xff1a; 非常喜欢的一道题&#xff0c;经典中的经典。打好基础&#xff0c;daydayup!!!啤酒问题&#xff1a;一瓶啤酒2元&#xff0c;4个盖子可以换一瓶&#xff0c;2个空瓶可以换一瓶&#xff0c;请问10元可以喝几瓶 题目如下&#xff1a; 啤酒问题&#xff1a;一瓶…

基于图的在线社区假新闻检测建模

论文原文&#xff1a;Graph-based Modeling of Online Communities for Fake News Detection 论文代码&#xff1a;GitHub - shaanchandra/SAFER: Repository containing the official code for the paper Graph-based Modeling of Online Communities for Fake News Detectio…

KIMI爆了!对比文心一言和通义千问它到底有多强?

原文:赵侠客 前言 最近国产大模型KIMI爆了大部分人应该都知道了&#xff0c;从我个人的感受来看这次KIMI爆了我不是从技术领域接触到的&#xff0c;而是从各种金融领域接触到的。目前国内大模型可以说是百模大战&#xff0c;前几年新能源大战&#xff0c;今年资本割完韭菜后留…

java面向对象编程基础

对象&#xff1a; java程序中的对象&#xff1a; 本质上是一种特殊的数据结构 对象是由类new出来的&#xff0c;有了类就可以创建对象 对象在计算机的执行原理&#xff1a; student s1new student();每次new student(),就是在堆内存中开辟一块内存区域代表一个学生对象s1变…

Matlab DDPG

文章目录 1 rlSimulinkEnv1.1 说明1.2 例子1.2.1 使用工作空间Agent创建Simulink环境1.2.2 为Simulink模型创建强化学习环境1.2.3 创建Simulink多Agents环境2 创建Simulink环境和训练Agent2.1 创建环境接口2.2 创建DDPG Agent2.3 训练Agent2.4 验证已训练的Agent3 创建Simulink…

创建linux虚拟机系统:(安装Ubuntu镜像文件,包含语言设置、中文输入法、时间设置)

我下载的是清华大写开源软件镜像站中的ubuntu-20.04.6-desktop-amd64.iso这个镜像文件&#xff0c; 这个文件我下载完成之后没有解压&#xff0c;直接在创建虚拟机的时候选择的压缩包。 地址为&#xff1a;Index of /ubuntu-releases/20.04/ | 清华大学开源软件镜像站 | Tsin…

Git——IDEA中的使用详解

目录 Git1、IDEA中配置Git2、将本地项目推送到远程仓库2.1、创建项目远程仓库2.2、初始化本地仓库2.3、连接远程仓库2.4、提交到本地仓库2.5、推送到远程仓库 3、克隆远程仓库到本地4、基本操作4.1、代码提交到暂存区4.2、暂存区代码提交到本地库4.3、推送到远程仓库4.4、撤销本…

网络: 网络层

IP地址: 分为网络号和主机号. 用来标识主机 IP协议 IP协议报文 4位版本号(version): 指定IP协议的版本, 对于IPv4来说, 就是4.4位头部长度(header length): IP头部的长度是多少个32bit, 也就是 length * 4 的字节数. 4bit表示最大的数字是15, 因此IP头部最大长度是60字节. 8…

HarmonyOS NEXT应用开发案例集

概述 随着应用代码的复杂度提升&#xff0c;为了使应用有更好的可维护性和可扩展性&#xff0c;良好的应用架构设计变得尤为重要。本篇文章将介绍一个应用通用架构的设计思路&#xff0c;以减少模块间的耦合、提升团队开发效率&#xff0c;为开发者呈现一个清晰且结构化的开发…

YOLOv8:Roboflow公开数据集训练模型

Roboflow公开数据集 Roboflow是一个提供计算机视觉数据集管理和处理工具的平台。虽然Roboflow本身并不创建或策划公开数据集&#xff0c;但它提供了一系列功能&#xff0c;帮助用户组织、预处理、增强和导出计算机视觉数据集。 官方网站&#xff1a;https://universe.roboflow…

FOCUS-AND-DETECT: A SMALL OBJECTDETECTION FRAMEWORK FOR AERIAL IMAGES

摘要 为了解决小对象检测问题&#xff0c;提出了一个叫做 Focus-and Detect 的检测框架&#xff0c;它是一个两阶段的框架。 第 一阶段包括由高斯混合模型监督的对象检测器网络&#xff0c;生成构成聚焦区域的对象簇 。 第二阶段 也是一个物体探测器网络&#xff0c;预测聚焦…

Web框架开发-Ajax

一、 Ajax准备知识:json 1、json(Javascript Obiect Notation,JS对象标记)是一种轻量级的数据交换格式 1 2 它基于 ECMAScript (w3c制定的js规范)的一个子集,采用完全独立于编程语言的文本格式来存储和表示数据。 简洁和清晰的层次结构使得 JSON 成为理想的数据交换语言。…