MYSQL基础入门_MySQL
虽然现在操作MySQl有可视化的软件,也有phpMyAdmin,但为了学习起见,还是了解应用下手写界面:)
在安装完MySQL之后,打开MySQL Command Line Client,首先要求输入的即是数据库用户密码。
在正确输入密码之后,显示为“mysql>”的命令行,表示MySQl已经准备好接受新的命令行了;当在此行输入了一条未完整的命令而进行换行时,将显示为“->”的命令行,这表示等待多行命令的下一行命令。
举个例子来说:显示MySQL中的所有数据库表,正常情况之下可以这样来表示:
mysql> show databases;
正常一个MySQL命令是由SQL语句组成,随后有一个分号的。当然,如果命令没有输入完整,将会出现如下情况:
mysql> show
-> databases
-> ;
在你输入一个多行查询的第一行后,要注意提示符如何从mysql>变为->,这正是mysql如何指出它没见到完整的语句并且正在等待剩余的部分。
还有,如果在输入多行命令突然不想执行而退出时,则可使用“c”命令行来解决,比如:
mysql> show
-> c
mysql>
此外,提示符“'>”表示等待下一行,收集以单引号(“'”)开始的字符串,提示符“">” 等待下一行,收集以双引号(“"”)开始的字符串。
尝试一些简单的MySQL命令:
mysql> SELECT version();
显示MySQL的版本
mysql> SELECT now();
显示当前时间
mysql> SELECT user();
显示MySQL的用户列表
mysql> SELECT 2*3;
计算并显示结果
mysql> SELECT now();SELECT user();
同时显示出当前时间和用户列表
最后,退出MySQL可以使用命令“quit”
mysql> QUIT
Bye

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics



With the rapid development of social media, Xiaohongshu has become one of the most popular social platforms. Users can create a Xiaohongshu account to show their personal identity and communicate and interact with other users. If you need to find a user’s Xiaohongshu number, you can follow these simple steps. 1. How to use Xiaohongshu account to find users? 1. Open the Xiaohongshu APP, click the "Discover" button in the lower right corner, and then select the "Notes" option. 2. In the note list, find the note posted by the user you want to find. Click to enter the note details page. 3. On the note details page, click the "Follow" button below the user's avatar to enter the user's personal homepage. 4. In the upper right corner of the user's personal homepage, click the three-dot button and select "Personal Information"

The Local Users and Groups utility is built into Computer Management and can be accessed from the console or independently. However, some users find that local users and groups are missing in Windows 11. For some people who have access to it, the message suggests that this snap-in may not work with this version of Windows 10. To manage user accounts for this computer, use the User Accounts tool in Control Panel. The issue has been reported in previous iterations of Windows 10 and is usually caused by issues or oversights on the user's side. Why are local users and groups missing in Windows 11? You are running Windows Home edition, local users and groups are available on Professional edition and above. Activity

In Ubuntu systems, the root user is usually disabled. To activate the root user, you can use the passwd command to set a password and then use the su- command to log in as root. The root user is a user with unrestricted system administrative rights. He has permissions to access and modify files, user management, software installation and removal, and system configuration changes. There are obvious differences between the root user and ordinary users. The root user has the highest authority and broader control rights in the system. The root user can execute important system commands and edit system files, which ordinary users cannot do. In this guide, I'll explore the Ubuntu root user, how to log in as root, and how it differs from a normal user. Notice

Certain folders are not always accessible due to permissions, and in today’s guide we will show you how to access user folders on your old hard drive on Windows 11. The process is simple but can take a while, sometimes even hours, depending on the size of the drive, so be extra patient and follow the instructions in this guide closely. Why can't I access my user folders on my old hard drive? User folders are owned by another computer, so you cannot modify them. You don't have any permissions on the folder other than ownership. How to open user files on old hard drive? 1. Take ownership of the folder and change permissions Find the old user directory, right-click on it and select Properties. Navigate to "An

Many users have been added to the Ubuntu system. I want to delete the users that are no longer in use. How to delete them? Let’s take a look at the detailed tutorial below. 1. Open the terminal command line and use the userdel command to delete the specified user. Be sure to add the sudo permission command, as shown in the figure below. 2. When deleting, be sure to be in the administrator directory. Ordinary users do not have this permission. , as shown in the figure below 3. After the delete command is executed, how to judge whether it has been truly deleted? Next we use the cat command to open the passwd file, as shown in the figure below 4. We see that the deleted user information is no longer in the passwd file, which proves that the user has been deleted, as shown in the figure below 5. Then we enter the home file

sudo (superuser execution) is a key command in Linux and Unix systems that allows ordinary users to run specific commands with root privileges. The function of sudo is mainly reflected in the following aspects: Providing permission control: sudo achieves strict control over system resources and sensitive operations by authorizing users to temporarily obtain superuser permissions. Ordinary users can only obtain temporary privileges through sudo when needed, and do not need to log in as superuser all the time. Improved security: By using sudo, you can avoid using the root account during routine operations. Using the root account for all operations may lead to unexpected system damage, as any mistaken or careless operation will have full permissions. and

Microsoft began rolling out KB2 to the public as an optional update for Windows 503145511H22 or later. This is the first update to enable Windows 11 Moment 4 features by default, including Windows Copilot in supported areas, preview support for items in the Start menu, ungrouping of the taskbar, and more. Additionally, it fixes several Windows 11 bugs, including potential performance issues that caused memory leaks. But ironically, the optional update for September 2023 will be a disaster for users trying to install the update, or even for those who have already installed it. Many users will not install this Wi

Microsoft invites WindowsInsider project members in the Canary and Dev channels to test and experience the new Paint application. The latest version number is 11.2306.30.0. The most noteworthy new feature of this version update is the one-click cutout function. Users only need to click once to automatically eliminate the background and highlight the main body of the picture, making it easier for users to perform subsequent operations. The whole step is very simple. The user imports the picture in the new layout application, and then clicks the "removebackground" button on the toolbar to delete the background in the picture. The user can also use a rectangle to select the area to remove the background.
